Testing Machine Research Articles

Co-Optimization of Speed Planning and Energy Management for Plug-In Hybrid Electric Trucks Passing Through Traffic Light Intersections

To tackle the energy-saving optimization issue of plug-in hybrid electric trucks traversing multiple traffic light intersections continuously, this paper presents a double-layer energy management strategy that utilizes the dynamic programming–twin delayed deep deterministic policy gradient (DP-TD3) algorithm to synergistically optimize the speed planning and energy management of plug-in hybrid electric trucks, thereby enhancing the vehicle’s passability through traffic light intersections and fuel economy. In the upper layer, the dynamic programming (DP) algorithm is employed to create a speed-planning model. This model effectively converts the nonlinear constraints related to the position, phase, and timing information of each traffic signal on the road into time-varying constraints, thereby improving computational efficiency. In the lower layer, an energy management model is constructed using the twin delayed deep deterministic policy gradient (TD3) algorithm to achieve optimal allocation of demanded power through the interaction of the TD3 agent with the truck environment. The model’s validity is confirmed through testing on a hardware-in-the-loop test machine, followed by simulation experiments. The results demonstrate that the DP-TD3 method proposed in this paper effectively enhances fuel economy, achieving an average fuel saving of 14.61% compared to the dynamic programming–charge depletion/charge sustenance (DP-CD/CS) method.

Effect of Annealing Temperature on Microstructure and Mechanical Properties of 00Cr21CuTi Stainless Steel Cold-Rolled Sheets

To investigate the evolution of microstructure and mechanical properties in cold-rolled sheets of Ferritic Stainless Steel (FSS) during annealing, a series of annealing tests were performed on 00Cr21CuTi at different temperatures of 930, 990, and 1050 °C. The changes in microstructure at these annealing temperatures were characterized by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron back-scattered diffraction (EBSD). The influence of annealing temperature on mechanical properties was assessed utilizing a universal tensile testing machine and a laser confocal microscope. The results indicated a gradual decrease in yield strength and tensile strength with increasing annealing temperature, whereas elongation exhibited an upward trend. At an annealing temperature of 930 °C, the yield strength, tensile strength, and elongation of the steel were 251 MPa, 409 MPa, and 30.9%, respectively, with a high product of strength plastic 12.64 GPa·%. This result represented an optimal balance between comprehensive strength and plasticity.

Practice Patterns and Trends in the Surgical Management of Mismatch Repair Deficient Colon Cancer

IntroductionDefects in the DNA mismatch repair (MMR) pathway can predispose individuals to colorectal cancer (CRC), with germline mutations in this pathway leading to Lynch syndrome. Consequently, universal MMR testing is recommended for all newly diagnosed CRC patients to detect mismatch repair deficient (MMR-D) tumors, enabling informed treatment decisions. Given the increased potential for metachronous disease in patients with Lynch syndrome, the current guidelines for surgical management of Lynch-associated colon cancer recommend extended resection in patients under age 60. MethodsA retrospective analysis of nonmetastatic CRC was performed from the National Cancer Database to evaluate the current trends and practice patterns in the surgical management of MMR-D colon cancer, as well as assess the factors influencing choice of surgical procedure. ResultsFrom 2018 to 2020, 98,112 nonmetastatic CRC patients were identified, with 19.93% being MMR-D. MMR-D colon cancer patients were more likely to undergo extended resection than those with mismatch repair proficient tumors (9.4% versus 4.2%, P < 0.001). When accounting for approximately one-fourth of MMR-D colon cancers being attributable to Lynch syndrome, the frequency of extended resection was less than expected (9.4% versus 25%, P < 0.001). MMR-D patients under age 60 were more likely to undergo extended resection than those over age 60 (9% versus 3%) (odds ratio [OR] 3.57, 95% confidence interval [CI] 3.06-4.15). Several factors were associated with decreased rate of extended resection: uninsured (OR 0.42, 95% CI 0.21-0.84), Black race (OR 0.54, 95% CI 0.35-0.82), treatment at nonacademic centers (OR 0.74, 95% CI 0.56-0.97), and crowfly distance >25 miles (OR 1.98, 95% CI 1.14-3.45). ConclusionsThese findings provide valuable insight into the current surgical practice patterns in the management of MMR-D colon cancers and possibly colon cancers associated with Lynch syndrome.

Impact of aging on the fracture strength of 3D-printed fixed implant prostheses: A comparative analysis of monolithic and bi-layer with or without fiber-reinforced composite frameworks.

This study aims to evaluate the fracture strength of three-unit, implant-supported fixed dental prostheses (FDPs) constructed from 3D-printed resin. It compares structures with and without fiber-reinforced composite (FRC) frameworks under conditions that mimic artificial aging. Forty FDPs were fabricated and divided into two groups: monolithic (n=20) and bi-layer (n=20). The monolithic group (MG) consisted entirely of FDPs made from 3D-printed resin for permanent restorations, while the bi-layer group (BG) featured FDPs with an FRC framework veneered with the same 3D-printed resin. Each group was subdivided into two subgroups: one subjected to artificial aging (MTG, n=10; BTG, n=10), and the other served as the baseline control (n=10). All subgroups underwent a mechanical bending test, applying a single load to failure using a universal testing machine. There was a statistically significant difference in fracture strength due to the presence of the FRC framework (p<0.01). The framework became the FDP more resistant to load. The mean load to failure and standard deviations were as follows: MG 406.59N (±33.84), MTG 286.20N (±152.15), BG 1142N (±162.88), and BTG 945N (±211.52). Although no statistical differences in strength were observed between aged and nonaged subgroups, variations in failure patterns emerged, with the BG and BTG groups showing a predominance of failures compared to the MG. The inclusion of an FRC framework significantly enhanced the fracture strength of the FDPs. While the aging protocol did not alter thestrength, failures predominantly occurred in the 3D-printed resin superstructure at the connectors. The highest rate of fractures occurred in the premolar connector.

Impact of chlorine dioxide and chlorhexidine mouthwashes on friction and surface roughness of orthodontic stainless steel wires: an in-vitro comparative study

Objectives Good oral hygiene measures are important for successful orthodontic treatment. They involve various types of mouthwashes which have been reported to cause alteration of mechanical properties of archwires. This study aimed to evaluate the effects of a new kind of chlorine-dioxide-containing mouthwash on the mechanical properties and surface morphology of stainless steel orthodontic archwires against the already prevalent chlorhexidine mouthwash in the market. Method Group A – Chlorhexidine mouthwash 0.2% (study), Group B – Chlorine Dioxide mouthwash (study), and Group C – Artificial Saliva (control). 42 specimens of 5 cm long 19x25 inch SS archwires were immersed in each group equally. Post immersion, the frictional force was analyzed in the universal testing machine for each group using custom-made acrylic jigs for 10 specimens. The remaining 4 specimens from each group were sent for surface morphology evaluation using an atomic force microscope. Results Friction resistance evaluation for the archwires revealed a mean friction of 0.011 ± 0.0056 in Group A, 0.015 ± 0.0052 in Group B, and 0.010 ± 0.0067 in Group C. Results suggested that the static friction of Group C (control group) was found to be the least when compared with the experimental groups, although not producing statistically significant values. Surface roughness of archwires compared at a 10μm range revealed a mean roughness of 19.38 ± 0.82 in Group A, 25.39 ± 7.01 in Group B, and 16.65 ± 3.07 in Group C which shows there wasn’t any statistically significant difference in the mean roughness midst the three sets. Conclusion Chlorine dioxide and Chlorhexidine mouthwashes caused an increase in the frictional resistance of the archwires when compared to the control group. This increase was statistically insignificant. When measured at a range of 10μm the mean surface roughness did not statistically differ across the control and the experimental groups.

SHEAR BOND STRENGTH OF DIFFERENT CALCIUM SILICATE BASED CEMENTS TO COMPOSITE AND COMPOMER

Aim:To evaluate shear bond strength(SBS)of three different calcium silicate cements(CSC)with different adhesive systems and restoratives. Materials and methods:NeoMTA2, NeoPutty and TheraCalPT were used as CSC.120 acrylic blocks with a hole in the middle were prepared and divided into three groups(n=40) depending on the CSC used.CSCs were placed in the prepared cavities. Each group was divided into two subgroups and adhesives(Prime&amp;BondNT) and Universal adhesive (Scotchbond)were applied.Then, composite(n=10) and compomer(n=10)were applied and polymerized.The prepared samples were kept at 37oC in a 100% humid environment for 24 hours and shear bond strength test(SBS) was performed with an universal testing device. Fracture types were evaluated using stereomicroscope and SEM.Results: TheraCalPT had statistically significant increased SBS values when compared to other materials(p0.05).The difference between the adhesive systems and the restorative materials themselves was not significant (p&gt;0.05).Conclusion:The ease of use of TheraCalPT and its strong bonding ability with resin restorative materials may provide support for the idea that it is suitable for pulp interventions.However, since in vitro environmental conditions do not reflect intraoral conditions,it must be supported by clinical studies to understand the actual performance and clinical usability.

An in vitro biomechanical evaluation of integrated lateral plate combined with oblique lateral interbody fusion in different bone conditions

Oblique lateral interbody fusion (OLIF) is a minimally invasive surgery for the treatment of lumbar degenerative diseases (LDD). Under normal bone mass(NB), supplemental with lateral plate (LP) fixation has been proven to provide stability and reduce complications. However, it is unclear whether OLIF combined with LP fixation can achieve satisfactory fixation effects in cases of osteoporosis(OP) or osteopenia (OS)? In this study, Eighteen L3-5 spinal specimens from 3 to 6 months old fresh calves were equally divided into 3 groups: group A (NB), group B (OS) and group C (OP). A load control scheme was adopted and evaluated using multidirectional nondestructive moments (± 7.5 N·m). An electronic universal tester and a tensile/torsion tester were simulated to generate 6 degrees of freedom of motion, and a VIC-3D three-dimensional optical full-field strain measurement system dynamically tracked the surgical segmental displacement. Each spine was evaluated under the following conditions at the L4-5 level: intact (INT); OLIF stand-alone (SA); cage supplemented with LP, cage supplemented with unilateral pedicle screws (UPS), and cage supplemented with bilateral pedicle screws (BPS). The current data show that With NB and OS models, LP fixation significantly reduced ROM in the LB and AR directions, with slightly less stability than BPS fixation and comparable to UPS. In the case of OP, LP fixation may increase the risk of internal fixation failure, and it is more preferable to choose BPS fixation with stronger stability.

INVESTIGATION ON THE STRENGTH OF E-GLASS FIBER/AA5052-H32 FIBER METAL LAMINATES CONNECTED USING RIVETED JOINTS

Fiber metal laminates (FMLs) belong to a class of composite materials comprising layers of metal sheets and fiber-reinforced polymers (FRP), configured in a specific sequence. This study investigates the tensile strength of FML specimens joined by riveted joints. FML plates were fabricated using AA5052 aluminium alloy, E-glass fibers, epoxy resin, and layered double hydroxide (LDH) via a hand layup process. The experimental parameters included the pattern of rivets, type of rivet materials, and rivet size. Tensile strength, the output response, was evaluated using Taguchi’s L9 orthogonal array design, followed by testing on a universal testing machine. The main effect plot and 3D surface plots were employed to analyze the tensile test results. Maximum tensile strength was held by the test specimen which was connected by the rivets made up of mild steel. From the ANOVA results presented in Table 6 , it was inferred that the number of rivets used for joining the FML specimens (pattern) played a major role in deciding the tensile strength of the specimens (57.25%). A regression equation, derived from Design Expert software, established the relationship between input variables and the tensile strength of FML specimens. ANOVA was conducted to assess the impact of each process variable on achieving optimal tensile strength. This research contributes novelty by integrating LDH into FML fabrication and demonstrates practical significance through systematic optimization of riveting parameters to enhance tensile strength. Quantitative and qualitative analyses underscore the effectiveness of the proposed FML configuration, validating its potential for structural applications.

Effect of air-particle abrasion and methacryloyloxydecyl phosphate primer on fracture load of thin zirconia crowns: an in vitro study

The study aimed to investigate the effects of airborne-particle abrasion (APA) and 10-methacryloxydecyl dihydrogen phosphate (10-MDP primer) surface treatments on the fracture load of thin zirconia crowns made from 3Y-TZP and 5Y-PSZ zirconia. Eighty full-contour zirconia crowns of 0.5 mm thickness were fabricated from 3Y-TZP and 5Y-PSZ zirconia. Crowns of each material were divided into four groups based on the surface treatment applied to the fitting surface (n = 10): Group 1 (control), Group 2 (10-MDP Primer Only), Group 3 (APA Only), and Group 4 (10-MDP Primer + APA). Crowns were cemented using self-adhesive resin cement and subjected to thermocycling. Fracture load tests were performed using a universal testing machine with a hemispherical indenter. Statistical analysis was performed using one-way ANOVA, Tukey's post hoc test, and independent samples T-test (α = 0.05). The fracture load of 3Y-TZP was significantly higher than 5Y-PSZ crowns across all groups (P ≤ 0.001). Group 1 had the lowest fracture load, while Group 4 had the highest for both materials. In 3Y-TZP, the fracture load of Group 2 increased by 40% (P = 0.002) and Group 3 by 50% (P &amp;lt; 0.001) compared to Group 1. Group 4 showed a 90% increase over Group 1 (P &amp;lt; 0.001). For 5Y-PSZ, fracture load of Group 4 increased by 70% compared to Group 1 (P &amp;lt; 0.001). It was concluded that applying a 10-MDP primer or APA significantly increases the fracture load of thin 3Y-TZP zirconia crowns, with the combination of both treatments yielding the highest values. For 5Y-PSZ, a significant increase in fracture load is observed only when both APA and the 10-MDP primer are used together.

Experimental Analysis of Mechanical Property Enhancement of Paper-Pulp-Based Packaging Materials Using Biodegradable Additives

Generally, paper-pulp-based materials are emerging in the packaging industry due to their high degree of biodegradability. Along with agricultural byproducts as an alternative, using additive or secondary materials in various processes and products has been a solution for implementing sustainability in material utilization. However, biodegradable materials still need to be improved due to the lack of properties which are essential for their use as packaging material. Currently, a number of research attempts have focused on enhancing the mechanical and thermal properties to increase the effectivity of those biodegradable materials for use as packaging material. The objective of this study is to analyze the effectivity of using sugarcane bagasse ash (SCBA) and wheat flour (starch) as a strengthening and thermal resistive additive. Due to its proven nano range particle size and fibrous nature, this material could positively affect the material properties. A total of twelve samples were prepared by varying the weight fraction of SCBA, white flour, and paper pulp. A compression molding method was used to prepare cylindrical samples with a diameter of 50 mm and a height of 55 mm under a compression load of 2 tonnes. Wet molded cylindrical blocks were oven-dried at 105∘C for 48 h to remove excessive moisture from the samples. Subsequently, all the samples were dried further until no significant weight loss was observed after the drying process to ensure their uniform moisture conditions. The prepared samples were tested for compressive strength using a Universal Testing Machine (UTM). Both load and compressive stress acting on each sample were plotted against the deflection of the sample. For the analysis, the deflection of each sample was measured at 8.6 kN load and the sample with 10% SCBA and 12.5% starch exhibited the least displacement among all additives. The results show that the samples with 10% SCBA and 12.5% starch also had the highest compressive strength compared to the other samples. Further, samples with the same amount of SCBA were analyzed for thermal resistivity and to obtain the thermal behavior of samples which is crucial in food packaging.Overall, most of the SCBA and starch mixed samples showed superior compressive strength compared to the pure paper-pulp-based sample.

Effect of Mechanical Surface Treatment on Shear Bond Strength of Orthodontic Brackets to 3D Printed and Milled CAD/CAM Provisional Materials: An In Vitro Study

The aim of the study is to assess the impact of mechanical surface treatments on the shear bond strength (SBS) of orthodontic brackets bonded to three-dimensional (3D) printed and milled CAD/CAM provisional materials. Sixty cylindrical samples were fabricated for each provisional material. Samples were treated with one of the following surface treatments: aluminum oxide airborne particle abrasion, diamond bur rotary instrument roughening, and phosphoric acid etching (control). Stainless steel brackets were bonded to the samples, and then SBS was tested using a universal testing machine. SEM and digital microscopy were utilized to examine the bonding interface and the failure modes. Two-way ANOVA, one-way ANOVA, Tukey’s HSD, and independent sample t-tests were used for statistical analysis. Results revealed significant differences in SBS between 3D printed and milled samples and significant differences in SBS among most surface treatments, with rotary instrument roughening resulting in the highest values for 3D printed, while airborne particle abrasion leading for milled samples. Digital microscopy indicated that more adhesive remained on 3D-printed samples. SEM analysis revealed varying surface roughness across treatments. Based on the findings of this study, it can be concluded that different surface treatments improve the bonding of orthodontic brackets to provisional crowns.

Effect of Dentin Bio-Modifiers Grape Seed Extract, Hesperidin on Shear Bond Strength and Microleakage: AScanning Electron Microscopic Assessment.

Investigation of different collagen cross-linking (CCL) agents, grape seed extract (GSE), Hesperidin (Hes), and rose bengal photosensitizer (RBP) on shear bond strength (SBS) and marginal leakage (ML) of composite bonded to carious affected dentin (CAD). Sixty-eight human molars in which carious lesions up to the middle third of the dentin were included. CAD was made flat followed by acid etching. Teeth were allocated randomly into four groups based on the application of CCL agents. Group 1: no CCL agent, Groups 2-4 samples treated with CCL agents. Bonding of adhesive and composite was performed followed by artificial aging. ML assessment was performed using a dye penetration test. SBS was evaluated using a universal testing machine followed by failure mode analysis. Analysis of the resin CAD interface with SEM was performed to identify the resin tag. For group comparisons, one-way ANOVA and post hoc Tukey test were used. The length and number of resin tags in GSE and Hes groups were greater than in the control and RBP. Furthermore, samples treated with GSE presented the highest scores of SBS and lowest ML. The control group presented the lowest bond integrity and highest ML. GSE and Hes positively influenced both SBS and ML.

Experimental study of aluminum alloys and their welded joints for compliance with roll-over protection structures requirements by GOST ISO 3471-2015

Background: Nowadays, tractor’s and construction machine’s cabins with integrated roll-over protecting structures are widely used. Using aluminum alloys for this load-bearing structures could tremendously reduce weight of the cabin, but usually it is not possible due to low mechanical properties of welded joint zone. Recently 3d-printing technologies of aluminum alloys appeared, that demonstrate high ductility and impact toughness. But their application in roll-over protecting structures requires additional research.Goal: research of stress-strain state of aluminum alloy specimens and their welded joint for compliance with roll-over protection systems of cabins requirements.Materials and methods: the experimental approach and simulations are used in this work. A universal tensile machine and impact testing machine are used in the experiment.Results: mechanical properties of samples made of 3d-printed aluminum alloys and their welded joints were obtained and their degree of compliance with passive safety requirements by GOST ISO 3471-2015 was established.Conclusions: 3d-printed aluminum alloys and their welded joints could be used in rollover protection structures of cabins in agricultural and construction machines.

Impact of Drill Bit Wear on Screw Withdrawal Resistance in Pinewood

Many factors affect screw withdrawal resistance (SWR), including screw size, embedment depth, the pre-drilled hole’s diameter, dimensional accuracy, and the furniture pieces’ material properties being joined. While prior research has extensively examined the influence of these factors, this study aimed to explore a neglected factor: how drill bit wear impacts pilot hole quality and subsequent SWR. The experimental setup included pinewood samples with pre-drilled 5 mm diameter blind pilot holes with a depth of 45 mm. The holes were equally divided into two groups: one drilled with a sharp bit, the other with a blunt bit. Euro-type coarse furniture screws (7 mm major diameter, 4 mm minor diameter, 3 mm pitch) were screwed into all holes. Subsequently, SWR was measured using a universal testing machine. Results show a statistically significant decrease in SWR when using the blunt drill bit. This phenomenon can be explained by excessive local material degradation, increased surface roughness, and disrupted hole dimensional accuracy, collectively hindering SWR. The study’s findings offer insights into how excessive drill bit wear impacts the screw withdrawal capacity of pinewood, informing best practices in furniture and construction.

Simulation and experimental evaluation of a vane-type magnetorheological damper based on multi-physics field coupling

This work aims to accurately evaluate the nonlinear behaviors of the vane-type magnetorheological (MR) damper through multi-physics field coupling analysis. The working principle of the vane-type MR damper is introduced, and the output torsion model is derived. Considering that the performance of the MR damper is affected by the coupling of electromagnetic field, flow field, thermal field, and solid mechanics, the finite element software COMSOL is used to simulate the multi-physics field inside the MR damper. Correspondingly, the mechanical performance testing of the MR damper is carried out on the torsional electro-hydraulic servo fatigue testing machine. The test results show that the MR damper can reach a maximum output torsion of 7130 N·m and achieves a high torsion-volume ratio of 4.19 × 107 N·m−2, which proves that it has good mechanical properties as well as the ability to satisfy high torsional requirements in relatively limited space. Finally, a comparative analysis between the simulation and experimental curves is carried out, and it is concluded that the multi-physics field coupling analysis can accurately simulate the mechanical performance and working state of the vane-type MR damper.

Flexural strength, surface roughness, and color stability of various CAD-CAM denture teeth materials.

To assess the flexural strength (FS), surface roughness, and color stability of additive manufactured (AM) and subtractive manufactured (SM) denture teeth materials, as well as the effect of thermocycling on these properties. Eighty strips (20/material type; 64×10×3.3mm) and 60 discs (15/material type; 12×4mm) were fabricated from four different denture teeth materials (Straumann, Flexcera, Ivoclar, and Candulor). The specimens were divided into two subgroups (nonthermal cycled and 5000 thermal cycled,10 per subgroup), and subjected to a 3-point test for FS using a universal testing machine at a crosshead speed of 5.0mm/min. Surface roughness (Ra, µm) and color differences (ΔE00) of disc specimens were measured before and after thermocycling using a noncontact optical profilometer and a spectrophotometer, respectively. The CIEDE2000 formula was used to calculate the color differences (ΔE00) before and after thermocycling. Data were analyzed using 2-way ANOVA followed by post hoc multiple comparison tests (α=0.05). There was no significant difference in flexural strength between nonthermal cycled SM materials (p=0.15), which were significantly higher than AM materials (p<0.001). The flexural strength values of all tested materials weresignificantly reduced after thermocycling (p<0.05). The material type had a significant effect on the Ra values (p<0.001), whereas thermocycling did not (p=0.81). After thermocycling, all materials exhibited color changes lower than the clinical perceptible threshold (ΔE00=2.7). Thermocycling decreased the FS of denture teeth materials manufactured with AM and SM, but did not affect the surface roughness. The FS values of SM groups were significantly higher than AM materials, irrespective of thermocycling. No clinically significant color changes of the denture teeth material were noted.

Caries affected Dentin biomodification using Bromelain, Riboflavin photosensitizer via UVA, and Chitosan Nanoparticles on shear bond strength and microleakage scores: A SEM evaluation.

Assessment of the impact of different dentin bio-modifiers i.e., Bromelain, Riboflavin photosensitizer (RFP/Ultraviolet-A), and Chitosan nanoparticles (CHNPs) on the shear bond strength (SBS) and microleakage of composite bonded to acid etched carious affected dentin (CAD). Sixty-four human molars in which carious lesions extend till the middle third of the dentin were included. The infected dentin was removed and CAD was exposed. All specimens were categorized into four groups based on the application of dentin bio-modifier (n=16) Group 1 (No dentin modifier), Group 2 (Bromelain), Group 3 (RFP/UVA), and Group 4 (CHNPs). Dental adhesive application and composite buildup were performed. A dye penetration test was used to assess marginal leakage. Resin CAD interface assessment was performed using SEM. For SBS and failure pattern analysis, a universal testing machine and stereomicroscope were used respectively. One-way ANOVA followed by Bonferroni's posthoc test was employed to analyze the differences among various groups (p ≤ 0.05) RESULTS: The lowest microleakage (13.27 ± 0.10) and highest SBS (11.64 ± 0.16 MPa) were observed in Group 2 (Bromelain). However, the maximum values of marginal leakage (37.21 ± 0.21) and minimum SBS (7.34 ± 0.07 MPa) were detected in Group 1 samples. The length of resin tags in the Group 2 specimens (Bromelain) was found to be the highest (102.11 ± 5.12μm). However, Group 1 (No modifier) exhibited the lowest resin tag length (50.45 ± 2.37 μm). Caries-affected dentin modified with Bromelain resulted in satisfactory SBS with minimal microleakage scores. Chitosan nanoparticles and RFP/Ultraviolet-A also presented better outcomes in terms of microleakage and SBS than the control.

Investigation of the mechanical properties of lavender-reinforced heat-activated polymethyl methacrylate denture base resin

Statement of problemThe antimicrobial efficacy of lavender has been well evidenced. However, investigations into its impact on the mechanical properties of denture resins are lacking. PurposeThe purpose of this in vitro study was to evaluate the flexural strength, impact strength, surface characteristics, roughness, elastic modulus, and yield strength of lavender-reinforced, heat-activated polymethyl methacrylate denture base resin. Material and methodsA total of 200 specimens were categorized into 5 groups based on 0, 0.5, 1.0, 1.5, and 2.0 wt% of dry lavender extract incorporated into heat-activated polymethyl methacrylate denture base resin powder. Unmodified resin served as the control group. Flexural strength, elastic moduli, and yield strength were determined with a universal testing machine, impact strength with an Izod impact tester, surface characteristics with scanning electron microscopy, and roughness with a profilometer. The data were statistically analyzed with 1-way ANOVA followed by Tukey post hoc tests for pairwise comparison within the groups (α=.05). ResultsCompared with the control group, all the mechanical properties significantly improved with the addition of lavender (P<.001). The highest flexural, yield, and impact strengths and elastic modulus values were in the 2% group. Elevated surface roughness in 0.5, 1.0 and 1.5 wt% and a decline in roughness at 2 wt% were noted when compared with the control group. ConclusionsThe addition of lavender enhanced the flexural strength, yield strength, impact strength, elastic moduli, and decreased surface roughness when added at 2 wt%.

The Effect of Synthetic Zeolite on the Curing Process and the Properties of the Natural Rubber-Based Composites.

Zeolites, known for their unique structural and catalytic properties, are added to the natural rubber matrix to investigate their influence on the vulcanization process and the resultant properties of composites. The natural rubber-based composites were masticated with 4A synthetic zeolite (0, 5, 10, 15, 20, and 30 phr). The curing of the rubber compounds was monitored on a moving die rheometer at 150 °C. The isothermal DSC method was also used to study the curing process at 150 °C, 160 °C, and 170 °C. Based on the obtained results, it is assumed that there is an interaction between the components of the curing system and the surface of the zeolite particle, and that is why the vulcanization reaction starts earlier with an increase in zeolite in the rubber mixture. This underscores the significant role of zeolite in accelerating the curing reaction of natural rubber-based compounds. The composites were vulcanized in a press at 150 °C for 15 min. The chemical structure was analyzed using FTIR, and the sample morphology was examined using SEM. The degree of swelling in toluene and distilled water was determined. The tensile strength values, modulus of elasticity at 100% and 300% elongation, and elongation at break were measured using a universal testing machine. Hardness was assessed according to the Shore A scale. With a small addition of zeolite (up to 10 phr), there is no significant change in the tensile strength values. However, adding a considerable amount of zeolite to a natural rubber matrix results in a deterioration of the tested mechanical properties. It can be assumed that with large proportions of zeolite 4A MS in the composites, the mechanical properties deteriorated due to increased porosity. The amount of added zeolite affects the initial stages of thermal decomposition of the examined samples and the rest after the analysis at a temperature of 500 °C.

Effects of femtosecond laser on hard dental tissues: A scoping review.

Traditional tooth preparation can cause patient discomfort, thermal damage to tissues, and occupational health risks for clinicians. Laser-based techniques, particularly femtosecond lasers, offer an alternative due to precise, non-invasive treatment without the thermal and mechanical drawbacks. The objective of this study was to assess available evidence on the effects of femtosecond laser treatment on enamel and dentin. The study design included in vitro or in vivo studies on human teeth reporting on qualitative and quantitative parameters of laser-dental tissue interaction. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) statement. The review was registered in the Open Science Framework registry. A comprehensive literature search of PubMed, Scopus, EMBASE/Ovid, Cochrane Library, DARE, LILACS and Pro Quest databases was conducted by three reviewers until 10th January 2024 and then updated on18th August 2024. Eligibility criteria included peer-reviewed articles published in English, focusing on human teeth, with available full text excluding reviews, conference proceedings and gray literature. The outcomes of interest were the quality of tooth preparation, surface characteristics, bond strength, thermal effects and damage to adjacent tissues with variables being laser parameters and tooth types. Methodological quality of studies was not conducted. The search yielded 48 articles after the removal of duplicates, irrelevant and non-retrievable articles. All were original in vitro studies investigating reporting on the outcomes of interest. Measurement methods included a range of microscopy, spectroscopy, optical coherence tomography, universal force testing and thermal imaging. Sapphire lasers were most commonly used with a wide range of parameters. Laser produced sharp-edged cavities with ablated surfaces free of melting (seen in approximately 10% of the craters), cracking, debris, with open dentinal tubules, increased wetting (Contact angle mean range 39.63 ̊(± 1.84 ̊) to 70.47 ̊(± 10.27 ̊) and roughness mean range 0.82 (± 0.05) to 4.20 (± 1.10)µm). Effects of femtosecond laser on bonding efficiency were inconsistent when compared to no treatment, conventional acid etching or Er:YAG laser. Femtosecond laser was shown to achieve precise tooth preparation with no or minimal thermal, mechanical and structural effects on adjacent tissue, however with variable bonding efficiency. Further research is needed to optimize laser parameters, investigate antibacterial effects, and establish long-term clinical outcomes and safety profiles.Date of registration: July 1st, 2024.Registration ID: OSF.IO/UQMNB.