Curing Mode Research Articles

Investigating the influence of various metakaolin combinations with different proportions of pond ash and Alccofine 1203 on ternary blended geopolymer concrete at ambient curing.

This paper explores the use of a ternary blended geopolymer concrete (TBGPC) incorporating metakaolin (MK), pond ash (PA), and Alccofine 1203 (AF). Three combinations of MK (25%, 50%, and 75%) with varying proportions of PA and AF were prepared, validating against M30 grade cement concrete (CC). TBGPC was prepared with an 8 molarity sodium hydroxide, sodium silicate to sodium hydroxide ratio of 2.0, liquid to binder ratio of 0.5, and an ambient curing mode. For CC, a water to cement ratio of 0.42 and water curing mode were adopted. The mechanical properties and durability behavior of TBGPC and CC specimens were evaluated through compressive strength, rapid chloride penetration test, permeability test, sorptivity test, and water absorption test. The M50P35A15 mix demonstrated remarkable compressive strength improvements, showing a 203% increase over the CC mix at 1day and 250% by 3days. This trend continued with a 155% increase at 7days, 68% at 28days, and 52% at 90days, consistently outperforming the CC mix. Additionally, microstructure characteristics of the M50P35A15 mix were analyzed through SEM studies, providing validation for the observed strength development. Notably, M50P35A15 mix demonstrated substantially higher early and later strength gain. This enhancement in strength was attributed to the gradual densification of the microstructure over time and the formation of additional NASH and CASH gel in M50P35A15 mix. At 28days, the M50P35A15 mix exhibited excellent durability characteristics, with a Coulomb value of 1008, permeability of 10mm, sorptivity of 0.45mm/√min × 10-4, and water absorption of 1.07%. This study demonstrates the potential of MK, PA, and AF as viable materials for sustainable geopolymer concrete, offering a low-carbon alternative to traditional cement concrete with superior strength and durability aspects.

МОДЕЛЮВАННЯ ТА ОПТИМІЗАЦІЯ РЕЖИМУ ТЕРМООБРОБКИ ТРУБЧАСТИХ ЕЛЕМЕНТІВ ФЕРМЕННИХ КОНСТРУКЦІЙ ЛІТАЛЬНИХ АПАРАТІВ З ВУГЛЕПЛАСТИКУ

The article analyzes the current state of development of dimensionally stable tubular elements (TE) and technological problems arising during their production. It is shown that along with empirical methods of studying the influence of various technological schemes on the dimensional stability of tubular elements, it is useful to use the optimal temperature-time mode for heat treatment and, based on it, select the optimal technological scheme. Modeling and determination of the optimal mode of heat treatment of tubular elements were performed. The study of the TE heat treatment mode was carried out in two stages, first by methods of mathematical modeling and optimization, and then by empirical enumeration of various technological schemes. At the first stage, the material properties, which are parameters of the mathematical model, were studied, and the optimal curing modes were calculated. At the second stage, the calculated optimal curing modes were supplemented with various technological methods that cannot be mathematically modeled, and a study was carried out on the influence of the resulting combined heat treatment mode on the geometric characteristics and dimensional stability of carbon fiber TE. The mathematical model of the process of heat treatment and curing of TE in a heat chamber, when heated by a heating air flow, is a system of differential equations: thermal conductivity and curing kinetics. A mathematical model of the process of heat treatment of tubular elements manufactured by the winding method is proposed, the ways of optimizing the curing mode of carbon fiber TE are shown. A numerical calculation of temperature-conversion fields during curing and calculation of optimal curing modes of tubular elements are performed taking into account various process schemes. The values of heat capacity C and thermal conductivity l are calculated depending on the temperature T, the degree of curing b and the filling coefficient g, Безфітингова ферма з вуглепластику Безфітингова ферма з вуглепластику Безфітингова ферма з вуглепластику the power of heat release W and the thermal effect of the curing reaction Q of carbon fiber. Optimum curing modes for a plate made of composite polymer material are obtained, calculated from the data obtained as a result of studying material samples. Temperature-time curing modes are obtained, which are optimized for different thicknesses of the studied material. The statistical hypothesis about the significance of the influence of the process flow chart and reinforcement pattern on the wall thickness of a tubular element and its compressive strength was proved by the dispersion analysis method. The influence of process flow charts and heat treatment modes on the geometric and mechanical characteristics of carbon fiber tubular elements of aircraft truss structures was studied. The statistical hypothesis about the significance of the influence of the process flow chart and reinforcement pattern on the deviation of the wall thickness of tubular elements and their strength characteristics was tested. The significance of the influence of process flow charts with different heat treatment modes on the average wall thickness of a carbon fiber tubular element was statistically proven.

Influence of luting strategies on dentin bond performance of self-adhesive resin luting cement in combination with a universal adhesive.

This study aimed to evaluate the dentin bond performance of various resin luting cement (RLC) systems combined with universal adhesives in different luting strategies. Three self-adhesive resin luting cements (SRLCs) were used with universal adhesives as primers. Twelve specimens per group were prepared to measure shear bond strength (SBS) under distinct luting strategies in etch-&-rinse and self-etch modes. Regarding luting strategies, the bonded specimens were categorized into four groups based on tooth primer application and the curing mode of the SRLC paste: (i) with light irradiation of the tooth primer (wL) + dual-cure mode (DC) of the SRLC paste, (ii) wL + self-cure mode (SC) of the SRLC paste, (iii) without light irradiation of the tooth primer (woL) + DC mode of the SRLC paste, and (iv) woL + SC mode of the SRLC paste. Specimens were also subjected to different storage conditions: 24h in water (baseline condition) and 10,000 cycles of thermal cycling. Luting strategy, storage condition, and SRLC system type significantly influenced dentin SBS values in both etching modes. Notably, certain SRLCs exhibited significantly higher dentin SBS when the primer was light-irradiated compared with no primer irradiation. Most SRLCs demonstrated higher dentin bond strength with light-irradiated primers, suggesting potential enhancement of dentin bond performance via primer light irradiation.

Development of Mineral Fillers for Acid-Resistant Filling Composites

This article presents the results of research on the development of chemically resistant polymer–mineral casting composites based on industrial waste. The aim of this work is to develop a technological basis for obtaining effective inorganic fillers and highly filled composites for use in chlorine-containing environments. On the basis of theoretical data, mineral fillers and a polymer binder for filling composites were selected, optimal quantities of input hardeners and an appropriate thermal curing mode were determined, and the influence of the filling degree on the properties of composites was studied. The influence of various factors on the properties of the obtained composites was also studied, and the possibility of using local raw materials to obtain special-purpose composites was investigated. Ash from a thermal power plant (TPP) was used as an acid-resistant filler in composites. Two components were chosen as binders: phenol formaldehyde resin and mineral filler (TPP ash). As the third component, hydrolytically active fillers—anhydrite, phosphogypsum and phosphate slag—were used. The degree of filling has a significant influence on the properties of composites, including the compressive strength, chemical resistance and degree of curing, the values of which were elucidated across a wide range of composite variations based on the degree of filling. The conducted research allowed us to establish the limit of admissible anhydrite content, which should not exceed 15 mas.%. To optimize the chemical resistance and durability of the composites of the investigated substances, the method of mathematical planning was used. According to the results of this study, the optimal compositions of composites, in terms of anhydrite, phosphogypsum and phosphorus slag contents, were selected. At the maximum possible degree of filling, these composites exhibit high target characteristics.

In English

Biopolymer matrices has been synthesized on the basis of ED-20 epoxy resin and soybean oil (SbO) bearing cyclocarbonate and epoxy groups. Mono(cyanoethyl)diethylenetriamine (UP) and tris(2-hydroxyethyl)amine (TEA) were used as hardeners. Chemical structure, mechanical properties, thermo-oxidative resistance of the samples and their changes after contact with distilled water, alkaline or acidic environment were studied. By means of ATR-FTIR the possible formation of H-NIPU (hybrid non-isocyanate polyurethane) fragments between cyclocarbonate groups of SbO and amino groups of the hardener was demonstrated. Influence of the curing mode and the type of hardener on water absorption, chemical and thermal oxidation resistance of the developed biopolymer matrices was thoroughly investigated. UP-based biopolymer matrices showed water and alkali resistance similar to the ones of neat epoxy polymers, while TEA-based biopolymer matrices showed better resistance to the acidic medium. The thermo-oxidative stability of the chosen samples was revealed by the TGA method in an air atmosphere. It was demonstrated that epoxy polymer cured with TEA hardener were more stable than the one cured with UP hardener. The similar dependence is observed for biopolymer matrices based on TEA hardener. At the same time, the curing mode has almost no effect on ultimate tensile strength value of the samples with ED-20/UP composition. However, the addition of functionalized SbO to the epoxy matrix cured with both TEA and UP hardeners increases the ultimate tensile strength values regardless of the type of oil functionalization. As expected, all biopolymer matrices exhibited higher ultimate tensile strength compared with unmodified epoxy polymers, which provides the possibility of their further application to obtain multi-layered bioplastics.

Mechanical Properties of Alkasite Material with Different Curing Modes and Simulated Aging Conditions.

This study aimed to evaluate the micro-mechanical and macro-mechanical properties of self-cured and light-cured alkasite and to investigate how accelerated degradation in acidic, alkaline, and ethanol solutions affects the macro-mechanical properties of self-cured and light-cured alkasite. The specimens of the alkasite material (Cention Forte, Ivoclar Vivadent) were prepared according to the following three curing modes: (1) light-cured immediately, (2) light-cured after a 5-min delay, and (3) self-cured. Microhardness was tested before and after immersion in absolute ethanol to indirectly determine crosslink density, while flexural strength and flexural modulus were measured using a three-point bending test after accelerated aging in the following solutions: (1) lactic acid solution (pH = 4.0), (2) NaOH solution (pH = 13.0), (3) phosphate-buffered saline solution (pH = 7.4), and (4) 75% ethanol solution. The data were statistically analyzed using a two-way ANOVA and Tukey post hoc test. The results showed that the microhardness, flexural strength, and flexural modulus were significantly lower in self-cured specimens compared to light-cured specimens. A 5-min delay between the extrusion of the material from the capsule and light curing had no significant effect on any of the measured properties. A significant effect of the accelerated aging solutions on macro-mechanical properties was observed, with ethanol and alkaline solutions having a particularly detrimental effect. In conclusion, light curing was preferable to self-curing, as it resulted in significantly better micro- and macro-mechanical properties, while a 5-min delay between mixing the capsule and light curing had no negative effects.

New Perspectives in Overcoming Bulk-Fill Composite Polymerization Shrinkage: The Impact of Curing Mode and Layering.

The purpose of this study was to investigate the effect of different light curing modes on the polymerization shrinkage of a bulk-fill composite and to evaluate the impact of two layering techniques on the cuspal deflection. Nine different light curing modes were tested on bulk-fill composite samples in aluminum MOD cavities. Intensity, duration, and illumination distance were the factors that changed during the different curing modes. The digital image correlation method was used to visually represent the displacement of carbon particles on the materials' surface caused by shrinkage along both the horizontal and vertical axes. For simulating cuspal deflection, a separate protocol was used, with a bulk and horizontal layering technique. The results showed that the largest horizontal displacements were present in the soft start group (6.00 ± 0.82 µm) and in the X-tra power group (5.67 ± 1.21 µm). The smallest horizontal displacements were detected in normal curing modes (4.00 ± 1.58 µm; 4.00 ± 2.68 µm). The largest vertical displacements, at the bottom layer, were present in the normal curing mode group with a 20 s curing time (5.22 ± 1.56 µm), while the smallest vertical displacements were shown in the X-tra power group (2.89 ± 0.60 µm). The observed particle displacements showing the shrinkage of the composite were correlated with the curing mode. The bulk-fill group showed less cuspal deflection than the horizontal layering group did, but the difference was not statistically significant (p = 0.575). Within the limitations of this in vitro study, it can be concluded that lower intensities of curing lights (1200 mW/cm2) may perform better from the point of view of material shrinkage than high and extreme light intensities do. The pulse delay mode might be recommended in the case of bulk-fill materials. The number of layers did not significantly affect the cuspal deflection in the case of the studied composite.

Temperature Changes in the Pulp Chamber During Orthodontic Bonding Using a High-Power Light-Emitting Diode Device With Two Different Exposure Times and Intensities: An In-Vitro Study.

This study used a high-power light-emitting diode (LED) device to evaluate the effects of two exposure times and intensities on pulp chamber temperature and cooling time during bracket bonding. Sixty upper premolars were used in the sample in this study. These premolars were split into two main groups based on the exposure time and intensity: the first group employed a traditional curing mode (TCG) for 20 seconds with an intensity of 1200 mw/cm2, whereas the second group had a quick curing mode (QCG) for 3 seconds with an intensity of 2500 mw/cm2. The pulp chamber's temperature variations and cooling times were recorded using a thermal imaging camera. The Mann-Whitney U test was used to find differences between the two-group comparison of the pulp chamber's temperature and cooling time. The two groups had statistically significant differences regarding the temperature increase in the pulp chamber and cooling time (p > 0.001). The mean temperature increase in the traditional curing group was 3.52°C, which is greater than that in the quick curing group (i.e., a mean value of 1.28°C). The mean cooling time in the traditional curing group was 38.83 seconds, which is greater than that in the quick curing group (9.97 seconds). Reducing the exposure time to 3 secondsand increasing the intensity to 2500 mw/cm2is considered safer for the pulp chamber during and after the curing process.

Effect of curing mode of resin composite cements on water sorption, color stability, and biaxial flexural strength

ObjectivesTo determine whether water sorption and solubility of a recently introduced self-adhesive cement is comparable to two clinically tested resin composite cements after thermal aging, and if this is affected by the curing mode. Whether water sorption is correlated with color difference and biaxial flexural strength was also investigated. MethodsWater sorption and solubility of three resin composite cements {RelyX Universal (RUV), (Panavia V5 (PV5), Panavia SA plus (PSA)} were measured after thermal aging. Disk-shaped specimens were either light-cured or autopolymerized (n = 15 per group). Color difference ΔE00 and biaxial flexural strength were also obtained. ResultsSorption was highest for RUV (auto: 54.9 ± 9.0 µg/mm3, light: 49.7 ± 4.9 µg/mm3), followed by PSA (auto: 37.7 ± 1.4 µg/mm3, light: 34.5 ± 1.1 µg/mm3) and PV5 (auto: 21.7 ± 0.7 µg/mm3, light: 22.1 ± 0.4 µg/mm3). Light-curing reduced solubility values, particularly for RUV (from 60.7 ± 20.8 µg/mm3 to 6.4 ± 0.8 µg/mm3). Color differences of ΔE00 > 1.8 (considered clinically not acceptable) were noted after aging for RUV and PSA. Sorption and ΔE00 values after aging were correlated linearly (R2 = 0.970). Biaxial flexural strength values were highest for PV5 (light: 153.4 ± 15.9 MPa; auto: 133.2 ± 18.0 MPa) and lowest for RUV (light: 99.3 ± 12.8 MPa; auto: 35.1 ± 8.3 MPa). SignificanceLight-curing has beneficial effects on sorption, color stability, and biaxial flexural strength of resin composite cements. Cements containing 2-hydroxymethacrylate such as RUV and PSA are more prone to water sorption and color changes.

Influence of dual-cure resin-cement curing modes on gingival cytotoxicity and inflammatory responses

Background/purposeDual-cure resin-cements are used for various dental restorations. However, whether the curing modes of these resin-cements influence gingival inflammation remains unclear. Hence, herein, we evaluated the effects of dual-cure resin-cement curing modes on gingival cytotoxicity and inflammatory responses. Materials and methodsSpecimens were prepared using two dual-cure resin-cements—RelyX Unicem 2 (RU) and G-CEM ONE (GO)—by light-cure or self-cure modes. Degree of conversion (DC) and monomer elution of the resin-cements were measured using Fourier-transform infrared spectroscopy and high-performance liquid chromatography, respectively. Human gingival fibroblasts (GFs) and macrophages were cultured on resin-cements, and inflammatory cytokine levels, intracellular reactive oxygen species (ROS) generation, and mitogen-activated protein (MAP) kinase activation were evaluated. ResultsLight-cured (LC) resin-cements exhibited significantly higher DC and lower monomer elution than did self-cured (SC) resin-cements. Triethyleneglycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) were substantially eluted from RU and GO, respectively. Neither LC resin-cement exhibited cytotoxicity and enhanced pro-inflammatory cytokine expression in GFs and macrophages. However, both SC resin-cements significantly decreased cell numbers and promoted cellular inflammatory responses. SC generated higher intracellular ROS levels compared to that seen with LC, and different patterns of MAP kinase activation were observed between SC–RU and SC–GO. ConclusionCompared with LC dual-cure resin-cements, SC dual-cure resin-cements show stronger cytotoxicity and elicit greater inflammatory responses in gingival cells owing to residual monomers (e.g., TEGDMA and UDMA) by activating MAP kinases in GFs and macrophages. Clinicians should ensure adequate light irradiation during prosthesis cementation and make efforts to remove the excess cement.

Blue Laser for Polymerization of Bulk Fill Composites: Influence on dentin bond strength and temperature rise during curing and co-curing method.

Blue diode lasers are alternative curing devices for dental composites. The aim of this study was to investigate the influence of blue diode laser polymerization on shear bond strength of bulk fill composites to human dentin and temperature rise during two types of polymerization. Composite cylinders of SDR Plus(SDR) and Ever X Flow(EX) were bonded to dentin slabs using Adhese Universal and curing devices blue diode laser (449nm, 1.6 W) and Power Cure LED. For each material and curing device there were two polymerization approaches: 1)conventional: separate curing of adhesive; 2)co-curing: simultaneous adhesive and composite curing. Polymerization modes for each material in conventional and co-curing(c) approach were: blue laser 2000 mW/cm2 for 5s (L5 and L5c); blue laser 1000 mW/cm2 for 10s (L10 and L10c); Power Cure 2000 mW/cm2 for 5s (LED5 and LED5c); Power Cure 1000 mW/cm2 for 10s (LED10 and LED10c). Temeperature was measured using thermal vision camera. For SDR, the highest bond strength was 24.3MPa in L10c, and the lowest 9.2MPa in LED5c. EX exhibited the highest bond strength(21.3MPa) in LED5, and the lowest in L5(7.7MPa). The highest temperature rise for SDR was in L10 and L5 (7.3 and 7.2°C), and the lowest in LED5(0.8°C). For EX, the highest temperature rise was in L5 (13.0°C), and the lowest in LED5 (0.7°C). Temperature rise was higher during blue laser polymerization, especially at high intensity and with conventional curing. Preferable blue laser curing mode is co-curing at 1000mW/cm2 for 10s.

Influence of different curing modes on the bonding effectiveness of self-adhesive resin luting cements in combination with universal adhesives

ObjectivesThis study aimed to investigate the immediate dentin bond performance and bond durability of self-adhesive resin luting cements (RLCs) in combination with universal adhesives in different curing modes. MethodsTwo self-adhesive RLCs were used with universal adhesives as primers. They were also used alone as self-adhesive RLCs. Two multiple-step RLC systems were used as comparison materials. To measure the shear bond strength (SBS) in different curing modes, 12 specimens were prepared for each group. Stainless-steel rods were bonded to bovine dentin, and the bonded specimens were assigned to the baseline group (stored for 24 h) and artificially aged group (thermal cycling [TC], 10,000 cycles). After each storage period, the SBS of the bonded specimens was measured. The Knoop hardness number (KHN) of the cured RLCs was measured with or without primer application in different curing modes at 24 h and after 10,000 TC. The representative RLC/dentin interfaces were observed using scanning electron microscopy (SEM). ResultsDentin SBS was significantly influenced by the RLC system but not by the curing mode. Self-adhesive RLCs alone showed significantly lower SBS values than self-adhesive RLCs with primer regardless of the curing mode or storage period. The storage period, curing mode, and RLC system significantly influenced the KHN. SignificanceThe use of universal adhesives as a primer may help enhance the immediate dentin bond performance and bond durability of self-adhesive RLCs.

Effect of dentin surface conditions and curing mode of resin cement on the dentin bond strength.

This study investigates the effects of dentin's drying time, roughness, and curing modes of resin cement on bond strength. Forty human teeth were divided into eight groups based on three experimental factors: dentin's roughness by 240-or 600-grit SiC paper (coarse or fine), dentin wetness with air-drying time (5-s or 10-s), and Single Bond Universal adhesive's curing mode by co-curing with RelyX Ultimate cement or light-curing separately (co-curing or light-curing). The micro-tensile bond strength of fifteen resin-dentin stikcs per groups was measured. Failure mode and adhesive layers were observed using stereoscopic and confocal laser scanning microscopy, respectively. The curing mode of the adhesive layer affected the bond strength of the dentin-resin cement (p<0.05). In particular, the light-curing mode exhibited a significantly higher bond strength than the co-curing one (p<0.05). The bond strength between the resin cement and dentin was improved in the 5-s drying groups than in the 10-s drying groups.

Assessing the Efficacy of Novel Fiber-Reinforced Dual-Cure Luting Resins.

Dual-cure resin-based luting materials are increasingly favored in clinical applications due to their capacity to establish a strong bond with natural tooth structure and restorations. This study aimed to examine certain physical and handling characteristics of newly developed experimental dual-cure luting resins reinforced with short fibers (SFRCs) and compare them with commercially available dual-cure luting resins. Seven dual-cure luting materials were tested (Relyx Ultimate, Duo-Link, eCEMENT, Variolink Esthetic, G-CEM LinkForce, experimental SFRC1, experimental SFRC2). Fourier transform infrared spectroscopy (FTIR) was utilized to determine the degree of monomer conversion (DC%) in the self and light-curing protocol. A rotating disk rheometer measured viscosity at room temperature (22°C) and simulated mouth temperature (35°C). Fracture toughness, flexural strength, and flexural modulus were evaluated using a 3-point bending test. Each luting resin was subjected to the examination of its surface microstructure using scanning electron microscopy (SEM). Analysis of variance (ANOVA) at a significance level of (p = 0.05) was conducted to analyze data. It was revealed that DC% of the tested dual-cure resins was significantly (p< 0.05) affected by the curing mode, the dual-cure SFRC2 having the highest and Relyx having the lowest DC (64%, and 41% respectively). The viscosity of all tested materials decreased with increasing temperature. SFRC2 demonstrated the highest fracture toughness (2.3 MPa m1/2), while Relyx Ultimate, Duo-Link, and eCEMENT exhibited the lowest values (≈ 1 MPa m1/2)(p< 0.05). Both SFRCs and G-CEM link-force exhibited the highest flexural strength values, and SFRCs resulted in the highest flexural modulus values (p<0.05). The experimental fiber-reinforced dual-cure luting resins exhibited superior DC%, fracture toughness, and flexural properties, yet, SFRC2 showed the highest viscosity at elevated temperature. These results highlight the capability of short fiber reinforcement to enhance the mechanical properties of dual-cured resin-based luting materials without compromising handling characteristics. Key words:Dual-cure luting resin; short fibers; degree of conversion; viscosity; fracture toughness; flexural properties.

Effect of Shade and Light Curing Mode on the Degree of Conversion of Silorane-Based and Methacrylate-Based Resin Composites

Effect of Shade and Light Curing Mode on the Degree of Conversion of Silorane-Based and Methacrylate-Based Resin Composites

Monitoring the internal structure behaviour of alkali-activated slag paste: effect of the curing mode

This paper deals with the monitoring of the internal structure behaviour of an alkaliactivated slag (AAS) paste. The slag was activated with a 4M solution of sodium hydroxide. The behaviour of the internal structure of the paste was regularly monitored through the changes in the resonant frequency and the mechanical properties, until the paste reached the age of 90 days. The main aim of the article is to show the long-term maturation and degradation process of an AAS paste under different curing modes. The results obtained suggest that the curing mode of the specimens has a significant effect on the behaviour of the internal structure of the paste based on the AAS. The development of both the dynamic properties and the flexural strength indicates the occurrence of a higher porosity in the internal structure of the paste, especially when the free drying process is started earlier. Insufficient hydration of the binder system is also a likely cause of cracks. The reduction in the relative dynamic moduli values ranging from 50 % to 80 % was observed for drying specimens at the age of 90 days. What is very interesting is that the occurrence of cracks was not prevented even by intensive moist curing of the paste as, between the 21st and the 28th day of maturing, there was a significant decrease of about 20 % in the relative dynamic modulus of elasticity and also a 50 % reduction in the flexural strength.

Effect of Curing Mode on Color Change of Two Different Bulk Fill Composites

Amaç: Bu çalışmanın amacı iki farklı kürleme modunda ışıklanan iki farklı bulk fill kompozit rezinin, 1 hafta boyunca distile su, şarap ve kahvede bekletilmesiyle meydana gelen renk değişimlerinin değerlendirilmesidir. &#x0D; Gereç-Yöntemler: Bu çalışmada A2 renginde iki farklı bulk fill kompozit rezin kullanılmıştır: Sonic Fill 2 (SF) (Kerr, ABD) ve Filtek Bulk Fill (FBF) (3M ESPE, ABD). Örnekler 5 mm çapında, 2 mm kalınlığında bir teflon kalıp kullanılarak hazırlanmıştır. Örnekler bir LED ışık cihazı (VALO Ultradent, South Jordan, UT) ile iki farklı kürleme modunda (standart güç modu-1000 mw/cm²-20 sn ve ekstra güç modu 3200 mw/cm²-3 sn) polimerize edilmiş, toplam 60 numune hazırlanmıştır. Renklendirme işlemlerine başlamadan önce örneklerin renk değerleri spektrofotometre (VITA Easyshade V, VITA Zahnfabrik, Almanya) kullanılarak ölçülmüştür. Ardından örnekler, üç farklı sıvıda 1 hafta boyunca bekletilmiştir. Renklendirme işlemleri tamamlandıktan 24 saat sonra renk ölçümü tekrarlanmıştır. Renk değişimi değerlendirmesi CIEDE2000 formülü kullanılarak yapılmıştır. Çalışmada elde edilen veriler SPSS Windows 25.0 (SPSS Inc., Chicago, IL, USA) programı kullanılarak analiz edilmiştir. Anlamlılık düzeyi p

Unlocking the Capacity of Bismuth Oxide by a Redox Mediator Strategy for High-Performance Aqueous Zn-Ion Batteries.

Many cathode materials store zinc ions based on the intercalation reaction mechanism in neutral aqueous Zn-ion batteries, and the structural design of the cathodes has been stuck in the curing mode by extending the ion diffusion channel. Here, we first develop halide ions to unlock the electrochemical activity of conversion-type Bi2O3 in aqueous Zn-ion batteries. Notably, the iodide ion shows the best performance compatibility with the Bi2O3 cathode. The electrochemical reaction mechanism studies show that iodide ions can be regarded as a redox medium to reduce the charge-transfer activation energy and motivate the conversion of Bi2O3 from Bi3+ to Bi0 during the cycle. Unsurprising, the discharge-specific capacity can reach 436.8 mAh g-1 at 0.5 A g-1 and achieve a cyclic lifespan of 6000 cycles at a current density of 3 A g-1. The activation of the Bi2O3 conversion reaction by iodide ions is of great significance for broadening the research range of ZIB cathode materials.

Effect of Two Different Ultrafast Curing Exposure Durations on the Surface Hardness of Bulk Fill Composite - An In-Vitro Study.

The aim of the present study is to assess the microhardness of resin-based composites (RBCs) cured with ultrafast curing mode at two different exposure durations. This is an experimental in-vitro study. Forty-five cylindrical composite specimens were prepared to a dimension of 5 mm height and 4 mm diameter. Curing was done using three different exposure modes and duration with dual mode LED curing light as follows: Group I: Ultrafast curing mode for 1 second at 2300 mW/cm2 (n = 15); Group II: Ultrafast curing mode for 3 second at 2300 mW/cm2 (n = 15) and Group III: Standard exposure mode for 20 second at 1000 mW/cm2 (n = 15). Vicker's microhardness measurement was done on both the curing and non-curing sides of the specimen using a motorised diamond-faced micro-indenter (Wilson Wolpwert, Germany) using a load of 50 gram and a dwell time of 30 second. Kruskal Wallis ANOVA was used to test for difference between the three groups followed by Mann-Whitney U test for post-hoc analysis. The microhardness values of the composite cured with a conventional curing unit were significantly higher than the ultrafast cured specimens. Low-intensity conventional curing lights were found to perform better than the high-intensity ultrafast curing units.

Synthesis, polymerization kinetics, and thermal properties of novel bismaleimides containing twisted structure

AbstractIn this study, two types of ortho‐oxazine functionalized bismaleimides with exceptional thermal properties and solubility were synthesized. The excellent solubility in many solvents is attributed to the stable twisted structure of the monomer. The monomer containing the cyano group showed enhanced solubility. It was found that the curing mode of ortho‐oxazine functionalized bismaleimide was autocatalytically cured. In situ FT‐IR spectroscopic studies indicated that the structure of bismaleimide resin undergoes a structural transformation at higher temperatures to form benzoxazole resin with enhanced thermal stability. The carbon residue rates of bismaleimide and benzoxazole resins at 800°C were 69% and 77%, respectively. The new bismaleimide and benzoxazole resins were analyzed using Microscale Combustion Calorimeter (MCC), and it was found that they also possess excellent flame‐retardant properties, specifically benzoxazole resin.