Chemical Bond Strength Research Articles

Features of electronic polarizability and approach to unique properties in tellurite glasses

AbstractTellurite glasses showing unique properties such as low phonon energy and high linear and nonlinear optical properties have been considered as promising materials for photonic device applications. The present article reviews the current status of the electronic polarizability in binary and ternary tellurite glasses and approaches their unique properties. Tellurite glasses consisting of basic modifier oxides (eg, Na2O, ZnO) and basic conditional glass forming oxide (TeO2) exhibit the features of high electronic polarizability and weak chemical bond strength, that is, refractive index‐based large oxide ion polarizability αO2‐(no), large optical basicity ∧(no), small interionic interaction parameter A(no), and small single bond strength BM‐O. The values of αO2‐(no), ∧(no), and A(no) in several tellurite glasses containing WO3, Nb2O5, and Bi2O3 were estimated in this article, and a good correlation was confirmed between ∧(no) and A(no). Unique properties of low glass transition temperature, fragile structural relaxation behavior, poor mechanical properties, high third‐order nonlinear optical susceptibilities in tellurite glasses were discussed from the point of electronic polarizability.

A novel spinel-type Mg0.55Al2.36O3.81N0.19 transparent ceramic with infrared transmittance range comparable to c-plane sapphire

A novel Mg0.55Al2.36O3.81N0.19 transparent ceramic with an infrared transmission range comparable to c-plane sapphire was prepared based on the intentional design of the composition. This material possesses outstanding optical properties, such as a high in-line transmittance up to 86.5% at 3.7 µm, a refractive index of 1.7240 at 589.3 nm and an absorption coefficient of 0.8 cm−1 at 5 µm. The effects of chemical composition on the crystal structure and optical properties of spinel material were discussed. In particular, the chemical bond strength of disordered tetrahedron varying with the composition largely determines the infrared transparent range of transparent ceramic.

Intramolecular Hydrogen Bonds in Normal and Sterically Compressed o-Hydroxy Aromatic Aldehydes. Isotope Effects on Chemical Shifts and Hydrogen Bond Strength.

A number of o-hydroxy aromatic aldehydes have been synthesized to illustrate the effect of steric compression and O···O distances on the intramolecular hydrogen bond and the hydrogen bond energies. Hydrogen bond energies have been calculated using the ‘hb and out’ method using either the MP2 method or the B3LYP functional with the basis set 6-311++G(d,p). However, several compounds cannot be treated this way. Hydrogen bond energies are also determined using electron densities at bond critical points and these results are in good agreement with the results of the ‘hb and out’ model. Two-bond deuterium isotope effects on 13C chemical shifts are suggested as an experimental way to obtain information on hydrogen bond energies as they easily can be measured. Isotope effects on aldehyde proton chemical shifts have also been measured. The former show very good correlation with the hydrogen bond energies and the latter are related to short O···O distances. Short O···O distances can be obtained as the result of short C=C bond lengths, conjugative effects, and steric compression of the aldehyde group. Short O···O distances are in general related to high hydrogen bond energies in these intramolecularly hydrogen-bonded systems of resonance assisted hydrogen bond (RAHB) type.

Effects of Bioactive Agents on Dentin Mineralization Kinetics After Dentin Bleaching.

This study evaluated effects of Bioglass 45S5 (BG) and Biosilicate (BS) remineralization on the chemical composition and bond strength of control dentin (CD) and bleached dentin (BD) surfaces. Dentin bleaching treatment was performed using the walking bleaching technique with 0.01 g of sodium perborate and 0.5 mL of 3% hydrogen peroxide for 14 days. Remineralization treatment was carried out by rubbing a remineralization solution (0.015 g of BG or BS diluted in 1.35 mL of distilled water) on the etched dentin surface for 30 seconds. Micro-Raman spectroscopy (MRS) was used to quantitatively analyze the mineral matrix ratios of CD and BD (n=5) after remineralization treatment with BG and BS over 15 days of incubation in artificial saliva. The CD and BD discs (n=10) with and without remineralization treatment with BG and BS were restored using a two-step etch-and-rinse adhesive system (Optibond S, Kerr) and five layers of 1-mm-thick composite resin (Filtek Z250, 3M ESPE). The restored dentin discs were sectioned into nine bonded beams with cross-sectional areas of approximately 0.9 mm2 and tested for microtensile bond strength (μTBS). The dentin surface of one fractured beam per tooth was submitted to MRS to characterize the physicochemical composition (n=10) at the interface. The data were analyzed using one-way analysis of variance and the Tukey-Kramer post hoc test (p<0.005). MRS bioactive analyses revealed that both BG and BS promoted increased mineral matrix ratios in the CD and BD. Significantly higher μTBS values were found after CD treatment with BG (CD: 57 MPa±11; CD-BG: 78 MPa±15) and when BG and BS were applied to the BD (BD: 42 MPa±5; BD-BG: 71 MPa±14; BD-BS: 64 MPa±11) (p<0.005). The MRS analysis of the fractured dentin beam showed that the remineralization treatment significantly increased the dentin relative mineral concentration and promoted the appearance of new interface peaks, indicating a chemical interaction (p<0.005). Remineralization of BD is an effective therapy to restore damage caused by dentin bleaching and acid conditioning. This approach not only increases dentin mineral compounds but also improves dentin's ability to interact chemically with the adhesive system.

Evaluation of the Impact of Consciousness Energy Healing Treatment on the Isotopic Abundance Ratios (PM+1/PM and PM+2/PM) of Ofloxacin

Ofloxacin is a class of fluorinated quinolone antibiotics, useful against most of the Gram-positive and Gram-negative bacterial infections. This study was designed to investigate the impact of the Trivedi Effect®-Consciousness Energy Healing Treatment on the structural properties and the isotopic abundance ratio of ofloxacin using LC-MS and GC-MS spectroscopy. Ofloxacin sample was divided into control and treated parts. The control ofloxacin did not receive the Consciousness Energy Healing Treatment, while the treated ofloxacin receives the Consciousness Energy Healing Treatment remotely by a renowned Biofield Energy Healer, Dahryn Trivedi. The LC-ESI-MS spectra of both the samples of ofloxacin at the retention time 3.05 minutes exhibited the mass of the protonated molecular ion peak at m/z 362.17 M+H+ (calculated for C18H21FN3O4+, 362.15). The LC-MS based isotopic abundance ratio of PM+1/PM in the treated ofloxacin was significantly increased by 56.57% compared with the control sample. Thus,2H, 15N, 13C, and17O contributions from (C18H21FN3O4)+ to m/z 363.17 in the treated ofloxacin were considerably increased compared with the control sample. The GC-MS based isotopic abundance ratios of PM+1/PM and PM+2/PM in the treated ofloxacin was significantly increased by 9.53% and 12.94%, respectively compared with the control sample. Hence,2H, 15N, 13C, 17O, and 18O contributions from (C18H21FN3O4)+ to m/z 318 and 319 in the treated ofloxacin were significantly increased compared with the control sample. The LC-MS and GC-MS based isotopic abundance ratios of PM+1/PM (2H/1H or 15N/14N or 13C/12C or 17O/16O), and PM+2/PM (18O/16O) in the treated ofloxacin were considerably improved compared to the control sample. The increased isotopic abundance ratio of the treated ofloxacin would increase the chemical bond strength and increase the stability in the body. The new form of treated ofloxacin would be more stable compared to the control sample and would be very useful to design improved pharmaceutical formulations that might offer better therapeutic response against infections of the urethra and cervix, infectious diarrhoea, urinary tract infections, cellulitis, chronic bronchitis, pneumonia, prostatitis, multidrug-resistant tuberculosis, plague, otitis media, etc.

Evaluation of brazed monolayer CBN grinding wheel on high-speed steel (HSS)

Shaping and forming of high-speed steel (HSS) tool with complicated geometry has been a challenge for the cutting tool industry. HSS grades generally display high hardness at high temperature and high wear resistance due to its constituent elements like a high amount of tungsten with the addition of chromium, vanadium and cobalt. HSS being used extensively in the manufacturing industry for machining difficult-cut-materials due to its high hardness and abrasion resistance. CBN grinding wheel is being used extensively for shaping the HSS. In this work, cBN brazed wheel with monolayer configuration is being used to grind HSS. Usually, reasonably uniform grit distribution, adequate spacing between the grits, 50-70% grit protrusion over the brazed surface and strong chemical bond strength are key features of brazed CBN wheel to perform satisfactorily. In the current investigation, the brazed CBN wheel showed limitations of its capability while grinding HSS in dry condition. The high chip load due to adverse grinding combinations, high attrition wear of grit due to its interaction with constituent elements like tungsten, chromium, vanadium and cobalt, fracturing and pull out of the grits are the limitation of the brazed wheel. The paper also concluded with facts to overcome limitations of brazed CBN wheel.

Bond-slip behaviour between FRP tubes and seawater sea sand concrete

In the present study the bond-slip behavior between FRP tubes and seawater sea sand concrete is studied using push-out tests. Pultruded and filament winding FRP tubes with different fibre orientations and diameter-to-thickness ratios (D/t) were constructed to investigate the effect of confinement pressure on the bond behaviour. Moreover, to study the effect of fibre type, three types of FRP (i.e.; GFRP, CFRP and BFRP) were used. In addition, the mechanical and chemical bond strength of concrete filled FRP tubes were quantified and compared. CFRP and BFRP tubes showed the highest and the lowest bond strengths, respectively. Furthermore, it was concluded that the real confinement pressure of the tubes has a significant effect on the bond strength: the greater the real confinement pressure, the larger the bond strength (i.e. the tubes with smaller D/t ratio and fibres orientated in 89° showed greater bond strength compared to the tubes with larger D/t and different fibres orientations). Repeating the push-out test for four times, for each sample, showed that the slip starts earlier by increasing the number of repetition, while the bond strength remained almost the same. This shows that the bond strength of tubes is mostly governed by the friction (confinement pressure) rather than the adhesion (chemical bond).

Stability of Selected Hydrogen Bonded Semiconductors in Organic Electronic Devices.

The electronics era is flourishing and morphing itself into Internet of Everything, IoE. At the same time, questions arise on the issue of electronic materials employed: especially their natural availability and low-cost fabrication, their functional stability in devices, and finally their desired biodegradation at the end of their life cycle. Hydrogen bonded pigments and natural dyes like indigo, anthraquinone and acridone are not only biodegradable and of bio-origin but also have functionality robustness and offer versatility in designing electronics and sensors components. With this Perspective, we intend to coalesce all the scattered reports on the above-mentioned classes of hydrogen bonded semiconductors, spanning across several disciplines and many active research groups. The article will comprise both published and unpublished results, on stability during aging, upon electrical, chemical and thermal stress, and will finish with an outlook section related to biological degradation and biological stability of selected hydrogen bonded molecules employed as semiconductors in organic electronic devices. We demonstrate that when the purity, the long-range order and the strength of chemical bonds, are considered, then the Hydrogen bonded organic semiconductors are the privileged class of materials having the potential to compete with inorganic semiconductors. As an experimental historical study of stability, we fabricated and characterized organic transistors from a material batch synthesized in 1932 and compared the results to a fresh material batch.

Analyses for oxygen vacancies in (Na,K)NbO3-series piezoelectric ceramics by soft x-ray emission spectroscopy

(Na0.55K0.45)NbO3 (NKN) and acceptor-doped (Na0.55K0.45)(Nb1-xZr5x/4)O3 (NKNZ; x = 0.005 and 0.01) piezoelectric ceramics were fabricated by the conventional solid-state reaction method. Both ceramics were applied to a fatigue test for 106 cycles under an electric field at 3 kV/mm with unipolar drive. After the fatigue test, the maximum polarization of NKN and NKNZ (x = 0.005) was decreased by approximately 15 and 5%, respectively. Therefore, we found that the fatigue resistance properties of NKNZ ceramics, which substituted the Nb5+ ion with the Zr4+ ion, were improved. To study fatigue phenomena in piezoelectric ceramics, the chemical bond strength of both ceramics before and after the fatigue test was analyzed by soft X-ray emission spectroscopy (SXES), which has high energy resolution and is suitable for the evaluation of light elements in a local region with the micrometer order. We evaluated the formation of oxygen vacancies in as-sintered, poled, and fatigued ceramics by analyzing a chemical shift of the O Ka(3) peak appeared at approximately 175 eV in the SXES spectra. In NKN ceramics, the O Ka(3) peak was shifted to the higher energy side by the poling treatment and fatigue test. The peak position of fatigued NKN ceramics was close to that of the standard SrTiO3 sample. It was considered that the oxygen vacancies of the fatigued NKN ceramics had accumulated at grain boundaries instead of the oxygen moving. The improvement of the fatigue resistance for the NKNZ ceramics was attributed to the formation of a defect dipole connected with the oxygen vacancy and acceptor Zr ion.

Effects of Different Surface Treatments on Bond Strength of Resin Cement to Machined Pure Titanium.

To investigate the effects of grit blasting, acidic or alkaline/heat treatments, and metal primer application on the shear bond strength (SBS) of resin cement to machined commercially pure titanium (CP-Ti). Titanium plates were machined and received one of the following treatments: grit-blasting (GB), or grit-blasting followed by either acidic treatment (GB/AC) or alkaline/heat treatment (GB/AH). The specimens were randomly divided into 4 groups and treated with Rely X Ceramic Primer (RCP), Z Prime Plus (ZPP), and Alloy Primer (ALP), or without primer as the control. The pairs of titanium plates were cemented together with the Rely X Unicem cement. SBS was measured before and after thermocycling between 5°C and 55°C for 5000 cycles. SEM observation showed that honeycomb-shaped pores formed on the surface of machined CP-Ti after GB/AC treatment, whereas a uniform net-like pattern formed after GB/AH treatment. In descending order, the surface roughness was GB, GB/AC, and GB/AH. The GB/AH group showed the highest SBS among all the treatments. As for primers, ALP group showed the highest SBS, while the RCP group showed the lowest. GB followed by ALP presented the highest SBS. A fine, uniform network structure was formed on the surface of CP-Ti following GB/AH treatment, providing an effective micromechanical interlocking mechanism for resin bonding. At the same time, after AH treatment, the -OH formed on the surface of the machined CP-Ti triggered a chemical reaction with the acid monomers in the resin adhesives, creating a chemical bond. As a result, GB/AH treatment significantly improved the bond strength relative to GB/AC treatment. In addition, ALP treatment facilitated the formation of hydrogen bonds, which further improved the chemical bond strength. Finally, the combination of the effects mentioned above resulted in the most robust bond between machined CP-Ti and the resin adhesives.

Structure and functional properties of protein from defatted Camellia oleifera seed cake: Effect of hydrogen peroxide decolorization

ABSTRACT This study aimed to analyze the effect of hydrogen peroxide decolorization on the structure and functional characteristics of tea meal protein to provide some theoretical basis for the utilization of tea meal protein. The changes in the protein structure and function before and after decolorization were evaluated by measuring denaturation temperature, surface hydrophobicity, and sulfhydryl content and by analyzing infrared spectrum, X-ray diffraction peak, and microstructure, etc. Results showed that decolorization with hydrogen peroxide increased the surface hydrophobicity, decreased the sulfhydryl content, and did not change the disulfide bond content. The treatment weakened the chemical bond strength but did not affect the basic skeleton structure. The microstructure as well as the position and intensity of the X-ray diffraction peak of the protein from Camellia oleracea seed cake remained the same before and after the treatment. The heat denaturation temperature also increased. Hydrogen peroxide did not change the isoelectric point; decreased the solubility, emulsifying properties, emulsion stability, foaming ability, and foam stability of the protein; and increased the oil and water holding capacities. Overall, decolorization with hydrogen peroxide did not significantly affect the protein structure but changed its functional properties.

Efficient degradation of phenol using Sn4+ doped FeOCl as photo-Fenton catalyst

Sn4+ doped FeOCl has been successfully synthetized as a sunlight-driven photo-Fenton catalyst, which shows that the catalytic activity of Sn4+/FeOCl (1.08% Sn4+ in the Sn4+/FeOCl) is a factor of 11.8 time higher than that of FeOCl. The doping of Sn4+ in FeOCl increases the optical adsorption and surface area of FeOCl. The decreased chemical bond strength of Fe-Cl in Sn4+/FeOCl effectively increases the number of exposed active sites (Fe-site and Sn-site), which boosts the production of OH radicals. The Sn-site shows higher catalytic activity than Fe-site. A synergistic mechanism for Sn4+/FeOCl is proposed for the enhanced catalytic performance.

Influence of bacterial incorporation on mechanical properties of engineered cementitious composites (ECC)

Incorporation of bacterial technology in concrete has attracted the attention of many researchers in the past decades. While much of the attention was focused on crack self-healing in concrete, it was also observed that such incorporation sometimes alters the mechanical properties of concrete significantly. There are very few studies related to the material performance of fiber reinforced concrete containing bacteria. In this paper, the bacteria were incorporated into engineered cementitious composites (ECC), and its mechanical properties were investigated systematically. At composite performance level, it was found that both compressive and tensile strength increased in bacteria-ECC, meanwhile the ECC with bacteria of higher activity presented more pronounced effect. Furthermore, crack pattern of ECC was also improved due to the addition of bacteria as smaller crack width was observed. In contrast, tensile strain capacity of bacteria-ECC reduced as compared with normal ECC, but still retained at high level. At microscale level, fracture toughness of matrix containing bacteria was higher than that of control mix. Additionally, matrix/fiber interface properties were altered in bacteria-ECC with lower chemical bond and higher frictional bond strength. The findings at microscale well explain the change in composite performance of ECCs based on micromechanics theory.

Ionic to covalent glass network transition: Effects on elastic and vibrational properties according to ultrasonic echography and Raman spectroscopy

In this study, ultrasonic echography and Raman spectroscopy were used to investigate the dependence of the elastic and vibrational properties on the composition of glass-forming pseudo-binary xSr(PO3)2-(1-x)(0.62MgF2-0.38AlF3) fluorophosphate glasses. The variation in Tg as the phosphate content increased indicated that the network in the glass structure was more interconnected. The decrease in the density with higher PO3−/F− ratios can be understood in terms of the less dense packing of the phosphate chains relative to the fluoride network and changes in the anionic volume in the glass network. The Raman spectra obtained for the fluorophosphate glasses confirmed the presence of PO4 tetrahedral species configurations with 2, 3, and 4 non-bridging oxygen atoms analogous to multicomponent mixed fluoride-phosphate glasses. A well-resolved Boson peak dominated the low-frequency Raman spectra. The transversal and longitudinal sound velocities exhibited the same composition-induced changes in the glass network as the density measurements. The variation in the bulk modulus as the PO3−/F− ratio increased indicated the transition from a strong (ionic-fluoride limit) to a less ionic (covalent-phosphate limit) structure, which was related to changes in the atomic volume. The glass network was characterized by a low cross-linking density according to the variations in Poisson's ratio. The incorporation of phosphate groups in the fluoride structure decreased the strength of the average chemical bond, as well as leading to a less interconnected network in the glass structure and reducing the strong ionic character of these fluorophosphate glasses, which was confirmed by the trend in the electronegativity difference and the attenuated propagation of the ultrasonic wave energy.

Toward a theory of mechanochemistry: Simple models from the very beginnings

AbstractA core idea in the context of mechanochemistry is that applying an external tensile force along a reaction coordinate should enhance the chemical reaction of interest. Here, we analyze perturbed generic molecular structures: schematic models of triatomics, ABC, and tetraatomics, AABB. They are used to demonstrate that pulling does usually not use the “reaction coordinate,” but opens new reaction pathways. Within development of these models we use the concept of Newton trajectories for a theory of mechanochemistry. However, we find cases where the theory of Newton trajectories is not applicable. For all cases, we define the curve of force‐displaced stationary points, and we discuss the importance of barrier breakdown points and valley‐ridge inflection points. The examples use Morse potentials for bonds and simple angle functions and are demonstrated by assumed real values for the potential parameters. On the basis of the systematic study of some generic models we explain a set of already observed experimental mechanochemical phenomena in specific molecular systems and we apply the results to the strength of chemical bonds.

Role of ion energy flux on the structural and morphological properties of silicon oxy-nitride composite films deposited by plasma focus device

ABSTRACTCrystalline silicon oxy-nitride (SiON) composite films are deposited on Si substrate for multiple (5, 15, 25 and 50) focus shots (FS) by plasma focus device. The X-rays diffraction patterns reveal the development of various diffraction peaks related to Si, Si3N4, and SiO2 phases which confirms the formation of SiON composite film. The intensity of Si3N4 (1 0 2) plane is linearly increased with the increase of FS. The Si3N4 (1 0 2) phase does not nucleate for 5 FS. Raman analysis confirms the formation of β–Si–N phase. Raman and Fourier transform infrared spectroscopy analysis reveals that the strength of chemical bonds like Si–N, Si–O formed during the deposition process of SiON composite films is associated with the bonds intensity which in turn depends on the number of FS. The field emission scanning electron microscopic analysis reveals that the surface morphology like size, shape and distribution of micro/nano-dimensional particles, film compactness and the formation of micro-rods, micro-teethes and micro-tubes of SiON composite films is entirely associated with the rise in substrate surface transient temperature which in turn depends on the increasing number of FS. The EDX spectrum confirms the presence of Si (22.5 ± 4.7 at. %), N (13.4 ± 4.5 at. %) and O (54.7 ± 11.3 at. %) in the SiON composite film. The thickness of SiON composite film deposited for 50 FS is found to ∼15.47 µm.

Structural properties and surface topography of MgO films prepared on Si (100) by pulsed DC magnetron sputtering

This work deals with the preparation of MgO films on Si (100) substrate by using pulsed DC magnetron sputtering of pure Mg target in reactive oxygen environment at room temperature. The sputtering power was varied in the range 100 W to 150 W while keeping the deposition time fixed at 4 h. In the next step, deposition time was changed from 1 h to 3 h by maintaining the sputtering power at 150 W. The results obtained were analyzed by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) techniques. The XRD pattern at 100 W exhibited MgO2 diffraction peak along (211) plane. However, with increase of power to 125 W and 150 W, MgO diffraction peak corresponding to (200) plane appeared. The crystallinity of MgO was improved with increase of the sputtering power. On contrary, the crystalline quality of MgO film was degraded with increase of the deposition time. The FTIR analysis displayed peaks around 860 cm−1 and 740 cm−1 corresponding to the characteristic of cubic MgO. With increase of deposition time from 1 h to 3 h, the peaks at 860 cm−1 and 740 cm−1 were disappeared, indicating a decrease in the strength of chemical bond between Mg and O. The AFM results revealed a decrease in the surface roughness with increase of both sputtering power and the deposition time.

Low-temperature InGaAs oxidation using oxygen neutral beam

The oxidation of InGaAs and the mechanisms underlying this process were investigated using a low-energy oxygen neutral beam. The thickness of the oxide layer and the components of In, O, Ga, and As were examined by cross-sectional transmission electron microscopy (TEM) and X-ray photoemission spectroscopy (XPS). Extending the oxidation duration together with the use of a high indium concentration generated a thicker InGaAs oxide layer because of the difference in chemical bond strength. The oxidation of InGaAs, which was successful even at room temperature, resulted in a high-quality interface because of the highly reactive neutral beam and its extremely low activation energy.

Physicochemical and structural features of the structure of enamel of permanent teeth and their hereditary conditionality

Aim. To determine the degree of influence of hereditary factors on the physicochemical and morphofunctional features of tooth enamel as a factor determining caries resistance or susceptibility to the carious process.Methods. To solve the problem, the degree of hereditary and environmental conditioning of the physico-chemical and structural properties of the enamel of intact and carious teeth was analyzed using the method of electron paramagnetic resonance on teeth removed by indications of a twin sample (30 monozygotic and 30 dizygotic pairs of twins). The method of electron paramagnetic resonance (EPR) allows one to obtain unique information about microscopic and macroscopic properties of tooth enamel, which cannot be obtained with the help of X-ray diffraction, spectral and other analyzes.Result. We found that the concentration of paramagnetic centers formed after irradiation is generally 1.5-2 times higher in enamel of carious teeth than in intact ones. The value of K, which characterizes caries susceptibility, is most pronounced when comparing the concentration of free radicals in the enamel of intact and carious teeth; incisors on the vestibular surface (1.35), in molars in the cervical region (1.97). As is known, the radiation resistance of solids can be characterized by the concentration of paramagnetic centers formed after irradiation. This stability, in turn, is related to the structure, chemical composition, strength of chemical bonds. Analysis of the results of twin studies showed that the intraparity differences in the concentration of free radicals of the F-center of the corresponding parts of the enamel of teeth in monozygotic pairs were significantly lower (1.6) than in identical sites of dizygotic twin pairs (7.0). High values of the heritability index (H-0.81) give grounds for making a conclusion about the significant contribution of hereditary factors to the indicator under studyConclusions. The physico-chemical and morphological properties of the enamel determine the susceptibility or stability of the teeth to carious lesions and experience a high degree of hereditary influences (H-81, H-0.95). Based on the data obtained, it can be concluded that the structure of the enamel is genetically determined. This indicates the need for an individual approach to the implementation of preventive measures with the allocation of risk groups to tooth decay

Non-selective rapid electro-oxidation of persistent, refractory VOCs in industrial wastewater using a highly catalytic and dimensionally stable Ir[sbnd]Pd/Ti composite electrode

Volatile organic compounds (VOCs) are highly toxic contaminants commonly dissolved in industrial wastewater. Therefore, treatment of VOC-containing wastewater requires a robust and rapid reaction because liquid VOCs can become volatile secondary pollutants. In this study, electro-oxidation with catalytic composite dimensionally stable anodes (DSAs)—a promising process for degrading organic pollutants—was applied to remove various VOCs (chloroform, benzene, toluene, and trichloroethylene). Excellent treatment efficiency of VOCs was demonstrated. To evaluate the VOC removal rate of each DSA, a titanium plate, a frequently used substratum, was coated with four different highly electrocatalytic composite materials (platinum group metals), Ir, IrPt, IrRu, and IrPd. Ir was used as a base catalyst to maintain the electrochemical stability of the anode. Current density and electrolyte concentration were evaluated over various ranges (20–45 mA/cm2 and 0.01–0.15 mol/L as NaCl, respectively) to determine the optimum operating condition. Results indicated that chloroform was the most refractory VOC tested due to its robust chemical bond strength. Moreover, the optimum current density and electrolyte concentration were 25 mA/cm2 and 0.05 M, respectively, representing the most cost-effective condition. Four DSAs were examined (Ir/Ti, IrPt/Ti, IrRu/Ti, and IrPd/Ti). The IrPd/Ti anode was the most suitable for treatment of VOCs presenting the highest chloroform removal performance of 78.8%, energy consumption of 0.38 kWh per unit mass (g) of oxidized chloroform, and the least volatilized fraction of 4.4%. IrPd/Ti was the most suitable anode material for VOC treatment because of its unique structure, high wettability, and high surface area.