Diluent Agent Research Articles

THE EFFECTIVENESS OF VITAMIN C AND E ADDITION IN VARIOUS DILUENTS OF BRAHMAN CATTLE SPERMATOZOA AFTER FREEZING

This research aimed to determine the quality of Brahman cattle spermatozoa after freezing in various diluent ingredients (Egg Yolk Citrate, Egg Yolk Tris, Skim Milk) which added vitamin C and vitamin E. The research was carried out using 4 treatments with 3 different diluent ingredients, each of which was Vitamins C and E are added to each diluent ingredient at a dose adjusted to the type of diluent agent. The treatment given is P0: Diluent without Vitamin C and E; P1: Diluent + Vitamin C; P2: Diluent + Vitamin E; and P3: Diluent + Vitamin C and Vitamin E. Research data were analyzed using analysis of variance and followed by Duncan's test at the 5% and/or 1% level for different variables. The results showed that the addition of vitamin C and vitamin E had a significant effect (P0.05) on motility and viability in the egg yolk tris diluent and egg yolk citrate but had no significant effect (P0.05) in the skim milk diluent. The use of different diluents had no significant effect (P0.05) on motility, viability, and abnormalities. This research concludes that Vitamin C added to the diluent tris egg yolk, egg yolk citrate, and skim milk showed higher average motility, percentage of live spermatozoa, and abnormalities of post-freezing Brahman cow spermatozoa.

Conditions Leading to Ketene Formation in Vaping Devices and Implications for Public Health.

The outbreak of e-cigarette or vaping use-associated lung injury (EVALI) in the United States in 2019 led to a total of 2807 hospitalizations with 68 deaths. While the exact causes of this vaping-related lung illness are still being debated, laboratory analyses of products from victims of EVALI have shown that vitamin E acetate (VEA), an additive in some tetrahydrocannabinol (THC)-containing products, is strongly linked to the EVALI outbreak. Because of its similar appearance and viscosity to pure THC oil, VEA was used as a diluent agent in cannabis oils in illicit markets. A potential mechanism for EVALI may involve VEA's thermal decomposition product, ketene, a highly poisonous gas, being generated under vaping conditions. In this study, a novel approach was developed to evaluate ketene production from VEA vaping under measurable temperature conditions in real-world devices. Ketene in generated aerosols was captured by two different chemical agents and analyzed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography with tandem mass spectrometry (LC-MS/MS). The LC-MS/MS method takes advantage of the high sensitivity and specificity of tandem mass spectrometry and appears to be more suitable than GC-MS for the analysis of large batches of samples. Our results confirmed the formation of ketene when VEA was vaped. The production of ketene increased with repeat puffs and showed a correlation to temperatures (200 to 500 °C) measured within vaping devices. Device battery power strength, which affects the heating temperature, plays an important role in ketene formation. In addition to ketene, the organic oxidant duroquinone was also obtained as another thermal degradation product of VEA. Ketene was not detected when vitamin E was vaped under the same conditions, confirming the importance of the acetate group for its generation.

Sumbawa black honey potency as a potential cyropreservative additive for hematopoetic stem cells (HSC) cryostorage

Background & Aim Cryopreservation or freezing (banking) HSC opens opportunities for future clinical applications (autologous HSC transplantation) or for parents and siblings (allogeneic HSC transplants). In the cryopreservation process, the cell is transferred into the cryo medium. Cryo medium comprises of basal medium added with a diluent medium (mainly fetal bovine serum, human serum albumin or umbilical cord blood serum) and DMSO cryoprotectant agent. DMSO is toxic to cells at room temperature and during transplant to the patient's body. Reports of side effects that arise include symptoms in the gastrointestinal tract, heart and blood vessels such as nausea, vomiting, ECG abnormalities, bradycardia and hypotension. DMSO is used in concentrations of 5% or 10% as cryoprotectant. DMSO concentration of 2% or less decreases the cell membrane integrity so that the cells are susceptible to lysis thus low cryopreservative potency. Extracellular cryoprotectants such as sucrose or trehalose combined with DMSO can reduce DMSO concentrations to 2.5%. This can reduce the toxicity caused by the DMSO cryoprotectant formula. Sumbawa black honey is a local product by Sumbawa honey farm that is known to contain high sucrose. This study aims to investigate the potency of Sumbawa black honey as cryopreservative additive to lower the concentration of DMSO in the cryo medium thus limit the toxicity potential. Methods, Results & Conclusion This is an experimental in vitro study from November 2018 until February 2019. The protocol has been approved by ethical committee Faculty of Medicine Universitas Indonesia and UCB donors have signed informed consent of the study. Enriched CD34+ hematopoetic stem cells were obtained by MACS CD34+ separation after ficoll density centrifugation. Cell count performed using tryphan blue exclusion methods. Flow cytometry analysis of CD34+ cells were performed after isolation and after thawing. Cryo medium composed of RPMI 1640, 10% DMSO and 10% UCB serum was used as control. Cryo medium composed of RPMI 1640, 10% UCB serum and either 5% DMSO or 2.5% DMSO added with 5% or 7.5% filtered Sumbawa black honey (for a total percentage of cryopreservative agent 10%).

Effectiveness of Two Type Coupling Agent of Dental Composite Nanofiller Prototype with Addition of Acetone in Preparation

Nano size of ceramic filler (nanofiller) are tend to possess difficulties to be covered by resin matrix due to large surface area to volume ratio. Addition of aceton known as the diluent agent by introducing more content of filler as well as helping distribution of the filler in the resin matrix in application of dental composite restoration. In this study, a total 24 specimens of dental composite prototype; nanofiller-TMPS and nanofiller-MPTS were prepared using a customized acrylic mold and they were divided into two groups based on filler/resin ratio (n=6 each group). In the process of dental composite making, acetone were added into resin; 1 ml (filler/resin, 50/50) and 5 ml (filler/resin, 80/20) untill specific consistency obtained. The specimens were stored in distilled water for 24 hours at 37°C then subjected to hardness test using Vickers hardness tester machine, LECO – Japan M– 400–H1 with the load of 200 grams for 15 seconds (ADA Specification No. 27). Data were statistically analyzed using t independent test (α=0.05). The result revealed that dental composite prototype contain nanofiller-MPTS with filler/resin rasio (50/50) were statistically significant higher than dental composite prototype contain nanofiller-TMPS with same ratio (p<0.05). Otherwise, dental composite prototype with filler/resin ratio (80/20) were no observed statistically significant differences for both nanofiller-TMPS and nanofiller-MPTS (p>0.05). As conclusion, nanofiller modified MPTS are more effective to elevate surface hardness of dental composite prototype than nanofiller-TMPS for 50/50 filler/resin ratio

On the self-propagating high-temperature synthesis of tungsten boride containing composite powders from WO3–B2O3–Mg system

In this research, the self-propagating high-temperature synthesis characteristics of the 2WO3‒(1 + x)B2O3‒(9 + y)Mg system were studied using H3BO3 as the boron oxide source. The addition of extra B2O3 and Mg was considered as the main process parameter to obtain tungsten borides phases. XRD results showed that tungsten element was the only phase remained after leaching of the products obtained with the stoichiometric composition. The extra B2O3 and Mg acted as the diluent agents and decreased the adiabatic temperature and the reaction velocity as well as the products’ particle size. Moreover, tungsten boride containing composite powders were obtained. However, the type of the tungsten boride in the composites was dependent on the diluent agent. Fourier transformed infrared spectroscopy analysis showed that nearly-pure composite powders were obtained after acid leaching. Finally, based on the XRD phase analysis and differential thermal analysis results, a mechanism was suggested for the formation of the SHS products in this system.

Preparation of epoxy-based insulator and optimization of its thermal property by Taguchi robust design method in double base propellant grain application

Taguchi method (orthogonal array, OA9) was used to design an epoxy insulator by evaluating its glass transition temperature (Tg) for using in a double base (DB) propellant grain. In this design method, three epoxy resins based on diglycidylether bisphenol A (DGEBA), three polyamine curing agents and a DGEBA-based reactive diluent agent were used. The curing process of epoxy resins with polyamines was studied by Fourier transform infrared spectroscopy. The results showed that the curing process was completed at room temperature. The effects of four parameters including resin type, curing agent type, curing agent concentration and diluent quantity were investigated to design a resin formulation with a highest Tg after curing. The obtained results were quantitatively evaluated by the analysis of variance (ANOVA). The results of ANOVA showed that the highest Tg of 86.0 ± 9.0 °C was obtained for the optimum formulation of MANA POX-95 as epoxy resin, H-30 as curing agent and 52 phr H-30. The Tg measured by the experiment was 78.0 ± 0.9 °C. In addition, the single lap shear strength (adhesion strength) of the optimized insulator was measured at 13.66 ± 1.02 MPa. Pull-off test performed on the surface of DB propellant resulted a 1.935 ± 0.003 MPa adhesion strength.

Self-microemulsifying sustained-release pellet of Ginkgo biloba extract: Preparation, in vitro drug release and pharmacokinetics study in beagle dogs

Ginkgo biloba extract (GBE50), the fifth generation extract of Ginkgo biloba, has been widely used in clinical treatment. This study was aimed at developing self-microemulsifying drug delivery system sustained-release pellets (SMEDDS-SR pellets) to achieve sustained release and increased the oral bioavailability of GBE50. Solubility studies and Pseudo-ternary phase diagrams were investigated to optimize the suitable compositions of SMEDDS-SR pellets. The optimal formulation of GBE50-SMEDDS consisting of oil (16.7% MCT), surfactant (33.4% Cremophor EL35), cosurfactant (33.4% PEG 400) and drug (16.7% GBE50) was obtained. The GBE50-SMEDDS-SR pellets were prepared by mixing GBE50-SMEDDS with diluent agent (MCC), disintegration agent (PVPP) and coating material of ethyl cellulose (EC) using extrusion spheronization method. The Morphology study of GBE50-SMEDDS-SR pellets after dispersion in water revealed a spherical and homogeneous structure of droplets (51.6 ± 1.8) nm. The in vitro release data revealed the sustained-release effect of GBE50-SMEDDS-SR pellets. Pharmacokinetics study in beagle dogs after oral administration yielded relative bioavailability (Fr) of 160.24% and 236.18% for GBE50-SMEDDS and GBE50-SMEDDS-SR pellets, respectively. Collectively, these results indicated that the SMEDDS-SR pellets could be an effective delivery system to achieve sustained release and improved oral bioavailability of GBE50.

Nickel ion removal using nanoporous poly(styrene-co divinyl benzene) copolymer

portions of diluent agent (porogen) were synthesized according to the methodology of the suspension polymerization technique. The structural characteristics of the particles and their adsorption properties for adsorption of Nickel ions were studied. Effect of solvent type and monomeric fraction on particles morphology and porosity was discussed. The solvents including n-heptane (HEP) and acetonitrile and monomer fraction was 50% and 30% of divinylbenzene (DVB). From the results obtained, we decided to apply an adsorbent with high mechanical strength and a porous structure appropriate for absorbing the Ni(II). The copolymer was characterized by Fourier transform infrared (FT-IR) analysis. We used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) tests to study the mor- phology and particle size of the nanoparticles. According to the results, the copolymers synthesized with n-heptane have more porosity. Also an increase in the percentage of DVB caused finer pores. After synthesis of copolymer the applicability of these polymer beads to separation and concentration of Ni(II) is discussed. In separation of Ni(II) from aqueous solution, the effects of pH, temperature and time are discussed and thermodynamic and kinetic calculations are done and its isotherm are fitted with various equations.

Investigation on mechanochemical behavior of the TiO2–Mg–C system reactive mixtures in the synthesis of titanium carbide

TiC–MgO composite was synthesized using mixtures of TiO2, Mg, and wood dust via a mechanochemical process. The influence of various Mg values (0–2.4mol) on the titanium carbide formation and the mechanism of reactions during the milling of TiO2–Mg–C mixture were investigated. Phase transformations, grain size, strain, lattice parameters, and morphology of the powders during the milling process were examined using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Thermodynamic calculations revealed that the Mg value played a main role. Consequently, the overall reaction enthalpy and adiabatic temperature (Tad) changed with variation of the magnesium content. Experimentally, after 10h of milling, TiC was synthesized in the mixture powder with stoichiometric ratio (Mg=2mol). The type of reactions was mechanically induced self-sustaining reaction (MSR). In addition, at lower Mg content (Mg=1.5), the heat resulted from magnesiothermic reaction also activated the carbothermal reduction. Further decrease in the Mg value (Mg=0.5 and 1mol) resulted in formation of MgTiO3 as a major phase. Using the excess Mg value (Mg=2.2 and 2.4molMg) as a diluent agent led to formation of Mg2TiO4 besides the MgO and TiC phases.

Liquid Membrane Component Selection for Succinic Acid Extraction

Succinic acid has received an upsurge interest in many industries due to its high product values and can be used in various applications. The purification cost for succinic acid from fermentation process was higher than the production cost, and the stock for succinic acid is limited. Thus, it is essential to develop an economical method to extract and purify the succinic acid. One of the promising methods is emulsion liquid membrane (ELM) process. In this study, ELM system will be developed to recover succinic acid from a simulated succinic acid fermentation broth through the selection of liquid membrane component using liquid-liquid extraction method. Several parameters such as different types of carrier, diluent, and stripping agent were investigated. The results show that the suitable carrier is Amberlite LA-2 with 87.2% of succinic acid extraction, the diluent is kerosene with 5% 1-octanol and the stripping agent is sodium hydroxide (NaOH) were selected as a main component for liquid membrane formulation.

Effect of the magnesium content on the mechanochemical behavior in ternary system Mg–B2O3–C

The influence of Mg content in Mg–B2O3–C mixture on the MgO–B4C composite formation and mechanism of reactions during ball milling process was investigated. In keeping with this aim, a mixture of boron oxide powder along with different amounts of Mg (4–10mol) and C (1–3mol) was activated in a ball mill. Thermodynamic calculations and differential thermal analysis (DTA) results revealed that Mg value played a main role, thereby; overall reaction enthalpy and adiabatic temperature (Tad) changed by variation of magnesium content. Tad enhanced with the increase in the Mg content and found maximum value (2852°C) at stoichiometric ratio (Mg=6mol). DTA results showed that increasing the activation time to 5.5h could decrease the temperature of combustion reaction to 530°C before magnesium melting. According to experimental findings, in the mixture of powder with 4mol Mg, magnesiothermic reaction occurred in MSR mode and no carbothermal reaction took place. However, when the Mg content reached within a range of 9/2–6mol, the magnesiothermic reaction occurred in MSR mode and activated the carbothermal reaction. Further enhancement in Mg content (10mol Mg), as a diluent agent, led to MSR magnesiothermic reaction and no carbothermal reduction occurred.

Dual-membrane reactor for methane oxidative coupling and dry methane reforming: Reactor integration and process intensification

A novel dual-membrane reactor concept was introduced for integrating the oxidative coupling of methane (OCM) and CO2 methane reforming (dry reforming) reactors. The OCM reactions occur in a conventional porous packed bed membrane reactor structure and a portion of the undesired produced CO2 and generated heat are transferred through a molten-carbonate perm-selective membrane and consumed in the adjacent dry methane reforming catalytic bed. This integrated reactor provides a very promising thermal performance by controlling the temperature peak to be below 50°C in reference to the average operating temperature in the OCM section. This was achieved even for the low methane-to-oxygen ratio 2 by introducing 10% CO2 as the diluent agent and reactant in this integrated reactor structure. This contributed to the improved selective performance of 32% methane conversion and 25% C2-yield including 21% C2H4-yield in the OCM section which also enhances the performance of the downstream units consequently. Around half of the unconverted methane leaving the OCM section was converted to syngas in the DRM section.The dual-membrane reactor alone can utilize a significant amount of the carbon dioxide generated in the OCM catalytic bed. In combination with adsorption unit in the downstream of the integrated process, 90% of the produced CO2 can be recovered and further converted to valuable syngas products. The experimental data, obtained from a mini-plant scale experimental facility, were exploited to verify the performance of the OCM reactor and the CO2 separation section.

Parametric studies on the synthesis of amidoximated adsorbent resins

AbstractThe main goal of this study was to obtain acrylonitrile (AN)‐divinylbenzene (DVB) copolymer beads that can serve as the matrix for preparation of amidoxime resins. AN‐DVB amidoxime resin was synthesized via suspension polymerization and the effect of different parameters such as the speed of stirrer, the amounts of suspending agent, hydrophilic agent, diluent agent, and initiator on its properties was investigated by fractional factorial (Taguchi) experimental design method. This method gives much‐reduced variance for the experiments with optimum control parameters setting and provides a set of minimum experiments compared to the conventional methods. The results showed that the most effective parameters on the amidoximation of resins were hydrophilic agent content, speed of stirrer, and the amount of suspending agent, respectively. Furthermore, anion‐exchange capacity of the amidoxime resins was utilized as a criterion for the evaluation of amidoxime adsorbent groups and the adsorption potential of the synthesized resins was determined by cation‐exchange capacity. The amount of methylacrylate as a hydrophilic agent had the most significant effect on the ion‐exchange capacity of the final product. Swelling ratio was also measured to evaluate the adsorption capacity of the synthesized resin. The results showed that the amounts of hydrophilic and diluent agents had significant effects on swelling ratio of resin. Finally, cation‐exchange capacity and swelling ratio of amidoxime resin were changed greatly because of alkaline treatment, but it had no significant effect on the anion‐exchange capacity of the synthesized resin. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Experimental investigation and CFD numerical simulation of WGSR for hydrogen enrichment of high CO2 content syngas from an air-blown updraft coal gasifier

The water gas shift reaction (WGSR) is an attractive process for enhancing the conversion of syngas carbon monoxide contents into carbon dioxide and hydrogen by means of steam in medium- and small-scale coal gasification power plants integrated with Carbon Capture and Storage (CCS) technologies.Fixed bed gasifiers, in fact, may become an interesting solution for medium- and small-scale applications in distributed power generation, although a syngas with a low LHV (about 6–7MJ/kg), high N2 (40–45%) and low H2 content, is generated when air is used, as usual, as oxidant. Syngas LHV can be enhanced by using oxygen (or oxygen enriched air) instead of air. However, when oxygen is used an appropriate amount of diluent agent as additional steam, recirculated syngas or CO2 is fed into the gasifier to control gasification temperature. In the case of syngas recirculation, the gasification process produces a syngas characterized by a high CO2 content, suitable for a more efficient separation.This paper concerns the experimental investigation and numerical simulation of carbon monoxide conversion and hydrogen generation from WGSR, when high CO2 content operating mixtures are considered. A baseline mixture was assumed that simulates the fuel gas produced by coal gasification in a small-scale air-blown updraft gasifier. During the experiments the fraction of N2 in the baseline mixture was gradually replaced with increasing CO2 fraction in order to investigate its effects of CO2 concentration on reaction and catalysts performances. An experimental apparatus, designed and built at the Department of Mechanical Engineering of the University of Cagliari (DIMECA), was used to investigate the main performance of WGSR, using high CO2-content operating mixtures and different catalyst types (Fe/Cr or Pt/Al for high temperature and Cu/Zn or Pt/Al for low temperature), and varying fundamental parameters, such as residence time of reactants in the catalyst bed, reaction temperature and H2O/CO ratio.The experimental results are supported by an in-depth numerical analysis. Numerical simulations were carried out using zero-dimensional (CSTR-based equilibrium model), one-dimensional (PFR-based) and CFD two-dimensional computational models to characterize the spatial and time-dependent behavior of the process.

Controlling of Nitriding Process on Reactive Plasma Spraying of Al Particles

Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of aluminum nitride (AlN) thermally sprayed coatings. To fabricate thick A lN coatings in RPS process, controlling and improving the in-flight nitriding reaction of Al particles is required. In this study, it was possible to control the nitriding reaction by using ammonium chloride (NH4Cl) powders. Thick and dense AlN coating (more than 300 μm thickness) was successfully fabricated with small addition of NH4Cl powders. Thus, addition of NH4Cl prevented the Al aggregation by changing the reaction pathway to a mild way with no explosive mode (relatively low heating rates) and it acts as a catalyst, nitrogen source and diluent agent.

Influence of NH4Cl Powder Addition for Fabrication of Aluminum Nitride Coating in Reactive Atmospheric Plasma Spray Process

Reactive plasma spray is the key to fabricating aluminum nitride (AlN) thermally sprayed coatings. It was possible to fabricate AlN/Al composite coatings using atmospheric plasma spray process through plasma nitriding of Al powders (Al 30 μm). The nitriding reaction and the AlN content could be improved by controlling the spray distance and the feedstock powder particle size. Increasing the spray distance and/or using smaller particle size of Al powders improved the in-flight nitriding reaction. However, it was difficult to fabricate thick and dense AlN coatings with an increase in the spray distance and/or when using fine particles. Thus, the coatings thickness was suppressed because of the complete nitriding of some particles (formation of AlN particles) during flight, which prevents the particle deposition. Furthermore, the excessive vaporization of Al fine particles (due to increased particle temperature) decreased the deposition efficiency. To fabricate thick AlN coatings in the reactive plasma spray process, improving the nitriding reaction of the large Al particles at short spray distance is required to decrease the vaporization of Al particles during flight. This study investigated the influence of adding ammonium chloride (NH4Cl) powders on the nitriding process of large Al powders and on the microstructure of the fabricated coatings. It was possible to fabricate thick AlN coatings at 100 mm spray distance with small addition of NH4Cl powders to the Al feedstock powders (30 μm). Addition of NH4Cl to the starting Al powders promoted the formation of AlN through changing the reaction path to vapor-phase nitridation chlorination-nitridation sequences as confirmed by the thermodynamic analysis of possible intermediate reactions. This changes the nitriding reaction to a mild way, so it is more controlled with no explosive mode and with relatively low heating rates. Thus, NH4Cl acts as a catalyst, nitrogen source, and diluent agent. Furthermore, the evolved gases from the sublimation or decomposition of NH4Cl can prevent the Al particles coalescing after melting.

Preparation and morphological characterization of narrow pore size distributed polypropylene hydrophobic membranes for vacuum membrane distillation via thermally induced phase separation

Isotactic polypropylene (iPP) hydrophobic microporous flat sheet membranes were developed via thermally induced phase separation for vacuum membrane distillation (VMD). The synthesized membranes were characterized by contact angle measurements, poremeter and scanning electron microscopy. The membranes had an asymmetric cross-sectional structure with cellular pores on the skin layer and dendritic pores on the non-skin layers. Pure water and 0.5 mol L − 1 aqueous NaCl solution VMD performance was developed with the resultant membranes. The factors of iPP concentration, iPP melt index and nucleating agent concentration affect pore morphology and performance of the membranes significantly. The formation of the membrane is not very sensitive to quench bath temperature, although temperature has a small effect on porosity. It was found that the diluent agent has a strong effect on the morphology and performance of the membranes; soybean oil is a good diluent agent for preparation of narrow pore size iPP hydrophobic membranes with pore size distribution of about 0.02–0.2 μm.

Solvent Versatility of Immobilized Amylose and Cellulose-Based Chiral Stationary Phases in Enantioselective LC Separation and Monitoring of Bio-Catalyzed Resolutions of Acidic Drugs in Non-Standard Organic Solvents

The solvent versatility of Chiralpak IA (amylose tris(3,5-dimethylphenylcarbamate)), Chiralpak IB (cellulose tris(3,5-dimethylphenylcarbamate)) and Chiralpak IC (cellulose tris(3,5-dichlorophenylcarbamate)) immobilized onto silica gel, are investigated for the enantioselective separation of a set of acidic drugs in liquid chromatography. Non-standard LC organic solvents like dichloromethane, ethyl acetate, tetrahydrofuran, methyl-tert-butyl ether were used in mobile phase compositions and/or diluent agent for the analyte on all new columns. Furthermore, the enantioselective separations of the reported compounds were compared on both immobilized columns (Chiralpak IA and IB) and their conventionally coated versions (Chiralpak AD-H and Chiralcel OD-H, respectively), using a mixture of n-hexane/2-PrOH/TFA (80:20:0.1 v/v/v). The versatility of the immobilized Chiralpak IB in monitoring reactions performed in non-standard solvent was studied on a representative example consisting of the lipase-catalyzed enantioselective esterification of flurbiprofen with n-butanol in methyl-tert-butyl ether as organic solvent.

Novel light-cured resins and composites with improved physicochemical properties

Objectives The aim of this study was to determine the effect of two new diluent agents (Bis-GMA analogues), at different dilution levels and filler contents on relevant physicochemical properties of several novel resins and composites containing Bis-GMA as matrix. Composites using TEGDMA as diluent were used as control. Methods Twenty formulations were prepared combining three monomer mixtures (Bis-GMA/TEGDMA, Bis-GMA/CH 3 Bis-GMA and Bis-GMA/CF 3 Bis-GMA), at three dilution levels (85/15, 10/90, 0/100) and two percentages of filler loading (silanated barium aluminosilicate glass): 0%, 10%, 35%. Preliminary rheological testing was performed in order to obtain the viscosity of the resin samples. Resins and composites were then inserted into molds and light-cured (500 mW/cm 2). The properties evaluated were: (1) homogeneity of curing (HC), using FTIR or Vickers microindentor, (2) microhardness, by a Vickers microindentor, (3) depths of cure and oxygen inhibitor effect (OIE), quantified by scraping, (4) water contact angle on the materials surface, (5) water sorption and solubility, performed by the Öysaed–Ruyter method and (6) scanning electron microscopy analysis of the specimens surfaces. Data were analyzed by ANOVA and Student–Newman–Keuls tests ( p < 0.05). Results Materials with CH 3 Bis-GMA and CF 3 Bis-GMA exhibited less hydrophilicity, water sorption and solubility. Bis-GMA dilution induced an increase in depth of cure and promoted a higher OIE, particularly when the diluent was TEGDMA. Filler loading reduced the OIE and increased hydrophobicity of the resins. Significance CH 3 Bis-GMA may be considered as good candidate to be used as diluent because when replacing TEGDMA-induced lower hydrolytic degradation and increase in HC.

Evaluation of two Bis-GMA analogues as potential monomer diluents to improve the mechanical properties of light-cured composite resins

The aim of this study was to investigate the influence of new diluent agents, diluent ratio and filler content, on relevant mechanical properties of several novel composite resins containing Bis-GMA as resin matrices, and to compare these with the properties of composites based on TEGDMA, a conventionally used diluent. Two Bis-GMA analogues were synthesized and 20 experimental composite resins were prepared combining three monomer mixtures (Bis-GMA/TEGDMA, Bis-GMA/CH3 Bis-GMA and Bis-GMA/CF3 Bis-GMA), at three dilution rates (85/15, 10/90, 0/100) and three levels of hybrid filler content (barium aluminosilicate glass): 0, 10 and 35%. Flexural strength (FS), modulus of elasticity (ME) and microhardness (VHN) of the composites were evaluated. Five specimens of each material were prepared for each mechanical test, light-cured over 120 s and stored in water at 37 degrees C for 1 week. Three-point bending test was used for FS measurement and VHN was quantified by using a Vickers microindentor. Data were analyzed by ANOVA and Student-Newman-Keuls tests (P<0.05). Materials with CH3 Bis-GMA showed an enhanced VHN. Mean FS was higher for matrices containing TEGDMA. Overall, dilution favored FS and VHN but not ME. Filler loading specially improved ME and VHN. Results correlate with an increase in the extent of polymerization due to the higher flexibility of the less viscous comonomer starting system and the hydrophobic character of the Bis-GMA analogues.