scholarly journals Modelling ATR-FTIR Spectra of Dental Bonding Systems to Investigate Composition and Polymerisation Kinetics

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 760
Author(s):  
António HS Delgado ◽  
Anne M. Young
Keyword(s):  
Light Exposure ◽  
Ftir Spectra ◽  
Dihydrogen Phosphate ◽  
Dental Bonding ◽  
Significance Level ◽  
Spectral Changes ◽  
Methacrylate Monomers ◽  
Main Components ◽  
Adhesive Model ◽  
Bonding Systems

Component ratios and kinetics are key to understanding and optimising novel formulations. This warrants investigation of valid methods. Attenuated Total Reflectance Fourier Transform Infra-Red (ATR)-FTIR spectra of separate primers/adhesives were modelled using summed spectra of solvents (water, ethanol), methacrylate monomers (HEMA (hydroxyethyl methacrylate), Bis-GMA (bisphenol A glycidyl methacrylate), and 10-MDP (10-methacryloyloxydecyl dihydrogen phosphate)), and fillers, multiplied by varying fractions. Filler loads were obtained following their separation from the adhesives, by analysing three repetitions (n = 3). Spectral changes during light exposure at 37 °C (20 s, LED 1100–1330 mW/cm2) were used to determine polymerisation kinetics (n = 3). Independent samples T-test was used for statistical analysis (significance level of 5%). FTIR modelling suggested a primer solvent percentage of OBFL (Optibond FL) (30%) was half that of CFSE (Clearfil SE 2) (60%). OBFL included ethanol and water, while CFSE included only water. Monomer peaks were largely those of HEMA with lower levels of phosphate monomers. OBFL/CFSE adhesive model spectra suggested that both contained equal volumes of Bis-GMA/HEMA, with CFSE having 10-MDP. Filler levels and spectra from OBFL (48 wt.%) and CFSE (5 wt.%) were different. Both systems reached a 50% conversion rate within seconds of light exposure. The final conversion for OBFL (74 ± 1%) was lower compared to CFSE (79 ± 2%) (p < 0.05). ATR-FTIR is a useful method to investigate relative levels of main components in bonding systems and their polymerisation kinetics. Such information is valuable to understanding such behaviour.

scholarly journals Methacrylate peak determination and selection recommendations using ATR-FTIR to investigate polymerisation of dental methacrylate mixtures

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252999
Author(s):  
António H. S. Delgado ◽  
Anne M. Young
Keyword(s):  
Repeated Measures ◽  
Light Exposure ◽  
Peak Height ◽  
Dihydrogen Phosphate ◽  
Difference Spectra ◽  
Significance Level ◽  
Noise Interference ◽  
Restorative Materials ◽  
Within Subjects ◽  
Urethane Dimethacrylate

Investigation of polymerisation kinetics using ATR-FTIR systems is common in many dental studies. However, peak selection methods to calculate monomer-polymer conversion can vary, consequently affecting final results. Thus, the aim of this study is to experimentally confirm which method is less prone to systematic errors. Three commercial restorative materials were tested–Vertise Flow (VF), Constic and Activa Bioactive Restorative Kids. Firstly, Attenuated Total Reflectance Fourier Transform Infra-Red (ATR-FTIR) (Spectrum One, Perkin-Elmer, UK) spectra of monomers were acquired—10-methacryloyloxy decyl dihydrogen phosphate (10-MDP), bisphenol-A glycidyl dimethacrylate (Bis-GMA), 2-hydroxyethyl methacrylate (HEMA), triethyelene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) to investigate proportionality of methacrylate peak heights versus concentration. Spectral changes upon light exposure of 2 mm discs of the restorative materials (irradiated for 20 s, LED curing unit 1100–1330 mW/cm2) were assessed to study polymerisation kinetics (n = 3), with continuous acquisition of spectra, before, during and after light exposure. Peak differences and degrees of conversion (DC %) were calculated using 1320/1336, 1320/1350 and 1636/1648 cm-1 as reaction/reference peaks. Inferential statistics included a MANOVA and within-subjects repeated measures ANOVA design (5% significance level). Proportionality of methacrylate peak height to concentration was confirmed, with the 1320/1352 cm-1 peak combination showing the lowest coefficient of variation (8%). Difference spectra of the polymerisation reaction showed noise interference around the 1500–1800 cm-1 region. Across the different materials, DC % results are highly dependent upon peak selection (p<0.001), with higher variability associated to the 1636 cm-1. Significant differences in the materials were only detected when the 1320 cm-1 peak was used (p<0.05). Within the same materials, methods were significantly different for Constic and Activa (p<0.05). It is possible to conclude that the 1320 cm-1 peak is more adequate to assess polymerisation of methacrylates and is therefore recommended.

scholarly journals Determination of Dental Adhesive Composition throughout Solvent Drying and Polymerization Using ATR–FTIR Spectroscopy

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3886
Author(s):  
Arwa Almusa ◽  
António H.S. Delgado ◽  
Paul Ashley ◽  
Anne M. Young
Keyword(s):  
Light Exposure ◽  
Light Emitting Diode ◽  
Attenuated Total Reflectance ◽  
Drying Time ◽  
Light Emitting ◽  
Spectral Changes ◽  
One Step ◽  
Urethane Dimethacrylate ◽  
Kinetics Of

The of this study aim was to develop a rapid method to determine the chemical composition, solvent evaporation rates, and polymerization kinetics of dental adhesives. Single-component, acetone-containing adhesives One-Step (OS; Bisco, USA), Optibond Universal (OU; Kerr, USA), and G-Bond (GB; GC, Japan) were studied. Filler levels were determined gravimetrically. Monomers and solvents were quantified by comparing their pure Attenuated Total Reflectance-Fourier Transform Infra-Red (ATR–FTIR) spectra, summed in different ratios, with those of the adhesives. Spectral changes at 37 °C, throughout passive evaporation for 5 min, then polymerisation initiated by 20 s, and blue light emitting diode (LED) (600 mW/cm2) exposure (n = 3) were determined. Evaporation and polymerisation extent versus time and final changes were calculated using acetone (1360 cm−1) and methacrylate (1320 cm−1) peaks. OS, OU, and GB filler contents were 0, 9.6, and 5.3%. FTIR suggested OS and OU were Bis-GMA based, GB was urethane dimethacrylate (UDMA) based, and that each had a different diluent and acidic monomers and possible UDMA/acetone interactions. Furthermore, initial acetone percentages were all 40−50%. After 5 min drying, they were 0% for OS and OU but 10% for GB. Whilst OS had no water, that in OU declined from 18 to 10% and in GB from 25 to 20% upon drying. Evaporation extents were 50% of final levels at 23, 25, and 113 s for OS, OU, and GB, respectively. Polymerisation extents were all 50 and 80% of final levels before 10 and at 20 s of light exposure, respectively. Final monomer polymerisation levels were 68, 69, and 88% for OS, OU, and GB, respectively. An appreciation of initial and final adhesive chemistry is important for understanding the properties. The rates of evaporation and polymerisation provide indications of relative required drying and light cure times. UDMA/acetone interactions might explain the considerably greater drying time of GB.

scholarly journals New 1,8-Naphthalimide Derivatives as Photoinitiators for Free-Radical Polymerization Upon Visible Light

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 637 ◽  
Author(s):  
Aude-Héloïse Bonardi ◽  
Soraya Zahouily ◽  
Céline Dietlin ◽  
Bernadette Graff ◽  
Fabrice Morlet-Savary ◽  
...  
Keyword(s):  
Free Radical ◽  
Visible Light ◽  
Radical Polymerization ◽  
Light Exposure ◽  
Free Radical Polymerization ◽  
Thermal Processes ◽  
Light Emitting ◽  
Chemical Mechanisms ◽  
Full Picture ◽  
Methacrylate Monomers

Photopolymerization processes, and especially those carried out under visible light, are more and more widespread for their multiple advantages compared to thermal processes. In the present paper, new 1,8-naphthalimide derivatives are proposed as photoinitiators for free-radical polymerization upon visible light exposure using light-emitting diodes (LEDs) at 395, 405, and 470 nm. These photoinitiators are used in combination with both iodonium salts and phosphine. The synthesis of these compounds as well as their excellent polymerization initiation ability for methacrylate monomers are presented in this article. A full picture of the involved chemical mechanisms is also provided thanks to photolysis, radical characterization, and redox measurements.

Pulpal and micro-organism responses to two experimental dental bonding systems

1989 ◽  
Vol 5 (2) ◽  
pp. 140-144 ◽  
Author(s):  
R.L. Blosser ◽  
N.W. Rupp ◽  
H.R. Stanley ◽  
R.L. Bowen
Keyword(s):  
Dental Bonding ◽  
Bonding Systems

scholarly journals Bond Strengths of Two Dental Bonding Systems

2000 ◽  
Vol 165 (7) ◽  
pp. 560-565 ◽  
Author(s):  
Denis Vojvodic ◽  
Vjekoslav Jerolimov ◽  
Domagoj Zabarovic ◽  
Ante Loncar
Keyword(s):  
Dental Bonding ◽  
Bond Strengths ◽  
Bonding Systems

Research on Deliquescent Polishing Fluid for KDP Crystals

2009 ◽  
Vol 626-627 ◽  
pp. 53-58 ◽  
Author(s):  
Shao Long Guo ◽  
Fei Hu Zhang ◽  
Yong Zhang ◽  
Dian Rong Luan
Keyword(s):  
Removal Rate ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
Performance Requirements ◽  
Stability Experiment ◽  
Main Components ◽  
Polishing Fluid ◽  
Kdp Crystals

The characteristics and principle of deliquescent polishing technology for potassium dihydrogen phosphate (KDP) crystals are introduced, and the performance requirements of deliquescent polishing fluid for KDP crystals are proposed. The main components of the deliquescent polishing fluid for KDP crystals were selected according to these performance requirements. Through uniformity experiment, stability experiment and fluidity experiment, uniformity, stability and fluidity of deliquescent polishing fluid for KDP crystals prepared using the selected components were tested. Through deliquescent polishing experiment of KDP crystal, polishing performance of deliquescent polishing fluid compounded using the selected components was tested. The material removal rate of the KDP crystal in the deliquescent polishing experiment was 6.03μm/min, and the surface roughness of the KDP crystal after deliquescent polishing was 4.857nm. The experimental results show that the compounded deliquescent polishing fluid for KDP crystals has good polishing performance and can reach the requirements.

scholarly journals Extraction of Lignin from Empty Fruit Bunch Fiber via Microwave-Assisted Deep-Eutectic Solvent Heating

2021 ◽  
Vol 1 (2) ◽  
pp. 18-25
Author(s):  
Muhammad Nor Arifin Yaakob ◽  
Rasidi Roslan
Keyword(s):  
Deep Eutectic Solvent ◽  
Crystallinity Index ◽  
Extraction Process ◽  
Ftir Spectra ◽  
Empty Fruit Bunch ◽  
Scanning Calorimetry ◽  
Microwave Assisted ◽  
A Value ◽  
1H Nuclear Magnetic Resonance ◽  
Main Components

This work study about the extraction of lignin from Empty Fruit Bunch (EFB). It is a type of lignocellulosic waste produced during the palm oil extraction process. There are three main components of lignocellulosic, which is one of them is lignin. A deep eutectic solvent (DES) with microwave-assisted heating has been used as a process to extract the lignin from EFB and turn it into a value-product. This convenient method was started with the mixing of EFB and DES. After that, the mixture was heated via microwave synthesis reactor at different temperature and time parameters. The extracted lignin yield was dried and ground into a powder form. The highest lignin yield recovered is 30 % by the highest time and temperature. Interestingly, the purity of all lignin yields are above than 80 %. The highest yield of lignin was characterized. According to Fourier-Transform Infrared (FTIR) spectra, there was a significant functional group of phenolic and aliphatic hydroxyl in lignin. Besides, the methoxy group was also configured in lignin spectra. The presence of conjugated alkene also conveyed the characteristic of lignin. The FTIR spectra were intensified with 1H Nuclear Magnetic Resonance (NMR) spectra where there was a chemical shift in lignin and raw EFB which was designated to aliphatic and aromatic protons bonded to a carbon atom. Three regions of decomposition occur in the Thermogravimetric Analysis (TGA) spectra. The initial decompose temperature of lignin was lower compare to raw EFB. Next, second-stage lignin decomposed at 434.14 ℃ with weight loss of 36.21 %. Lastly, for the final stage, lignin decomposes at 552.54 ℃. Moreover, Differential Scanning Calorimetry (DSC) spectra demonstrate that the Tg value of lignin managed to be identified. However, the Tg value of raw EFB cannot be well defined. As for the characterization in residual fractions of EFB, the lowest crystallinity index (CrI) value of raw EFB has proven the presence of lignocellulosic in its structure. The residual fractions that reacted at higher temperatures have an inflated value of CrI as they contain abundant left out cellulose.

scholarly journals The transcriptional dynamics of two filmy ferns from Hymenophyllaceae with different niche preferences unravel key aspects of their desiccation tolerance and vertical distribution along host trees

2017 ◽  
Author(s):  
Giovanni Larama ◽  
Enrique Ostria-Gallardo ◽  
Graciela Berrios ◽  
Ana Gutierrez ◽  
Ingo Ensminger ◽  
...  
Keyword(s):  
Gene Expression ◽  
Vertical Distribution ◽  
Water Loss ◽  
Desiccation Tolerance ◽  
Light Exposure ◽  
Single Layer ◽  
Interspecific Differences ◽  
Transcriptional Dynamics ◽  
Main Components ◽  
Key Aspects

ABSTRACTFerns from the Hymenophyllaceae family are one of the main components of the epiphytic species diversity in the Chilean temperate rain forest. Having membranous fronds of a single layer of cells, they show a poikilohydric strategy most typical from bryophytes. Although Hymenophyllaceae species shows the ability to tolerate desiccation, there are interspecific differences in their water loss kinetic. Counter-intuitively, those species that have rapid desiccation kinetic are able to reach higher host height and tolerate higher light exposure and vapor pressure deficit. Therefore, what are the mechanisms (constitutive and/or induced) responsible of the desiccation tolerance in this fern family? As this primitive fern family is closely related with mosses, it can be hypothesized that desiccation tolerance in this particular group would be associated with constitutive features rather than induced responses during dehydration. However, the inter-specific differences in water loss and vertical distribution would be associated to different degrees of induction either within the dehydration or rehydration phases. We applied an ecophysiological transcriptomic approach to study the dynamic of gene expression in two species of filmy ferns with contrasting desiccation kinetics and vertical distribution on the host tree. Our analysis identified commonalities and differences in gene regulation, and key genes correlated with the fronds hydration state, providing the patterns of gene expression responding to microenvironmental signals and behind the physiology of their resurrection strategy

scholarly journals Selective colorimetric molecular probe for cyanide ion detection in aqueous solution

2018 ◽  
Vol 9 (4) ◽  
pp. 338-346
Author(s):  
Yousef Mohammad Hijji ◽  
Hani Darwish Tabba ◽  
Rajeesha Rajan ◽  
Hamzeh Mohammad Abdel-Halim ◽  
Musa Ibrahim El-Barghouthi ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Aqueous Media ◽  
Molecular Probe ◽  
Dihydrogen Phosphate ◽  
Cyanide Ion ◽  
Absorption Bands ◽  
Spectral Changes ◽  
Yellow Color ◽  
Sensitivity And Selectivity

5-Nitro-2-hydroxybenzaldehyde (1) demonstrated to be a sensitive, and a selective molecular probe for cyanide ion (CN-) in aqueous media. In acetonitrile, compound 1 shows sensitivity and selectivity for cyanide, acetate and fluoride, in comparison to other investigated anions using both visual and spectroscopic means. In aqueous solution, the color becomes intense yellow upon addition of cyanide, while acetate showed this effect to a much lower extent. Significant spectral changes were also detected with the appearance of two new absorption bands at 358 and 387 nm. This was accompanied by concomitant intensity decrease for the band at 314 nm. Fluoride, dihydrogen phosphate, chloride, bromide, perchlorate, and azide showed negligible color and spectral changes for the probe in aqueous solutions. On the other hand, hydrogen sulfate caused fainting of the yellow color and gave a spectrum similar to that of the sensor in polar aprotic solvents. The cyanide ion was detected at micro molar levels in aqueous solutions with a stoichiometry of 1:1 for CN: probe in acetonitrile as the solvent. Cyanide, hydroxide, acetate, fluoride and dihydrogen phosphate showed identical changes to color and spectra, indicating a hydrogen bonding and a deprotonation mechanism.

scholarly journals Influence of Light Exposure during Cold Storage of Minimally Processed Vegetables (Valeriana sp.)

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Angela Zappia ◽  
Alessandra De Bruno ◽  
Rosita Torino ◽  
Amalia Piscopo ◽  
Marco Poiana
Keyword(s):  
Light Exposure ◽  
Bacterial Count ◽  
Total Bacterial Count ◽  
Antioxidant Compounds ◽  
Minimally Processed ◽  
Significance Level ◽  
Total Antioxidant ◽  
Hue Angle ◽  
Minimally Processed Vegetables

Minimally processed vegetables are sensitive to leaves discoloration and quality deterioration, and these negative aspects can affect their shelf life. During the manufacturing processing, Valeriana leaves were submitted to different dipping acid solutions and then were stored at cold temperature in dark and in light to study the influence of the light exposure on their quality in terms of total free acidity, dry matter percentage, colour, water activity, total bacterial count, antioxidant components, and total antioxidant activity. The results suggest that dark storage is recommended for a better physicochemical quality of Valeriana leaves. In particular, light influenced significantly the browning index and hue angle with a significance level of p<0.01 and p<0.05, respectively, whereas both exposure conditions affected total bacterial count and pH (p<0.01). Dipping treatments had an effect on pH, aw, and total bacterial count, while the storage time influenced with highly significant differences the most of the studied parameters, except for the antioxidant compounds.

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