Single Bond Strength Research Articles

Synthesis and optical properties of novel Bi2O3–Li2O–Al2O3–TeO2 glasses

Quaternary glasses of xBi2O3–20Li2O–5Al2O3–(75-x)TeO2 with varying compositions were produced by melt quenching. The purpose was to investigate their physical and optical characteristics. FTIR analysis was employed to examine the structural features of the glass system, followed by UV–Vis spectroscopy for verification of its optical properties. Density measurements performed with a densitometer revealed a rise from 4.68 g/cm³ to 5.06 g/cm³ as the Bi2O3 concentration increased. The refractive index value elevated from 2.6731 to 2.6975 alongside a notable rise in the Urbach energy range from 0.46 to 0.96 eV. As the amount of Bi2O3 varies from 0 to 5 mol%, there was a corresponding rise in the presence of BiO6 units associated with non-bridging oxygen atoms. This observation coincided with a weakening of the bismuth single bond strength, dropping from 283.54 kJ/mol to 158.71 kJ/mol. The optical transmittance decreases to 0.6518, while the reflection loss increases to 0.2108, with an increase in bismuth concentration from 0 to 5 mol%. As the bismuth content increases, both the polarizability of oxide ions and their optical basicity rise consistently, with polarizability values increasing from 2.9163 to 3.0910 Å3 and optical basicity values climbing from 1.0974 to 1.1297. The calculation of interaction parameters indicated that the inclusion of Bi2O3 in glass samples resulted in a shift from high covalency to ionicity, attributed to Bi2O3 acting as a glass modifier.

Study of Conditional Glass Formers (II) on Basics of Optical Electronegativity

Concept of Electronegativity is used by so many researchers to calculate Refractive index Band energy, Dielectric constant, Metallization criterion, Basicity, Oxide ion polarizability, Bond ionicity, Third order non-linear optical susceptibility to study the so many glass systems. Here the concept of optical electronegativity is used to study these parameters for conditional glass formers refer as (II) of group V(A,B) and VI(A,B). They are Ta2O5, Nb2O5, V2O5, Cr2O3, Bi2O3, TeO2, MoO3, As2O3, WO3, Se2O3. It is observed that on decreasing the values of optical electronegativity, optical band energy, metallization criterion, and bond iconicity decreases; and optical dielectric constant, optical basicity, oxide ion polarizability refractive index, third order non linear optical susceptibility increases. All conditional glass forming oxides (II) are according to Pauling's packing rule, Goldschmidt radius ratio rule, Zachariasen's random network theory and rules for formation of glass and Sun’s single bond strength theory. For Conditional glass formers (II) radius ratio rc/ra = 0.250-0.492, [except Bi2O3 (0.75) & TeO2 (0.87)] and single bond strength greater than 90 Kcal/mol. According to Sun’s, high bond strength oxides are not good glass formers because they themselves do not forms glass; but when they forms small ring in the melt of these materials which would result in easy crystallization. Key Words: Refractive index Band energy, Dielectric constant, Metallization criterion, Basicity, Oxide ion polarizability, Bond ionicity, Third order non-liner optical susceptibility.

STUDY OF GLASS FORMERS ON BASICS OF OPTICAL ELECTRONEGATIVITY

Concept of electronegativity is used by so many researchers to study Refractive index, Band energy, Dielectric constant, Metallization criterion, Basicity, Oxide ion polarizability, Bond ionicity, Third order non-linear optical susceptibility to study so many glass systems. Here the concept of optical electronegativity is used to study these parameters in glass formers. It is observed that on decreasing the values of optical electronegativity; optical band energy, metallization criterion, and bond ionicity decreases; where as optical dielectric constant, optical basicity, oxide ion polarizability refractive index and third order non linear optical susceptibility increases. All glass forming oxides are according to Pauling's packing rule, Goldschmidt radius ratio rule, Zachariasen's random network theory and rules for formation of glass and Sun’s single bond strength theory. For glass formers radius ratio rc/ra = 0.14-0.40, [except P2O5] and single bond strength greater than 90 Kcal/mol. Key Words: Band energy, Basicity, Optical dielectric constant, Oxide ion polarizability, Refractive index.

Study of Conditional Glass Formers (I) on Basics of Optical Electronegativity

Concept of Electronegativity is used by so many researchers to calculate Refractive index, Band energy, Dielectric constant, Metallization criterion, Basicity, Oxide ion polarizability, Bond ionicity, Third order non-linear optical susceptibility to study the so many glass systems. Here the concept of optical electronegativity is used to study these parameters for conditional glass formers referred as (1) taken from group III (A,B) and IV (A,B); they are Y2O3, HfO2, ZrO2, Sc2O3, TiO2, Al2O3, In2O3, Ga2O3, and SnO2. It is observed that optical band energy, metallization criterion, and bond iconicity decreases; and optical dielectric constant, optical basicity, oxide ion polarizability refractive index and third order non linear optical susceptibility increases. All conditional glass formers (I) oxides are according to Pauling's packing rule, Goldschmidt radius ratio rule, Zachariasen's random network theory, rules for formation of glass and Sun’s single bond strength theory. For conditional glass formers (I) radius ratio rc/ra = 0.40-0.75 and single bond strength greater than 90 Kcal/mol. According to Sun’s, high bond strength oxides are not good glass formers because they themselves do not forms glass; but when they forms small ring in the melt of these materials which result in easy crystallization. Key Words: Refractive index Band energy, Dielectric constant, Metallization criterion, Basicity, Oxide ion polarizability, Bond ionicity, Third order non-liner optical susceptibility.

Optical and structural properties of yttrium doped zinc lead borate glasses

A series of glass samples of the composition 60 % B2O3 - 35 % Pb3O4 – (5-x) % ZnO – x % Y2O3 with x = 0, 0.5, 1, 1.5, 2, 2.5, and 3 was prepared by the melt quenching technique. The amorphous nature of the prepared samples was confirmed by X-ray diffraction technique. The structural changes in the glass network were inspected by the density and molar volume measurements, as well as by the FT-IR analysis. The density of the prepared samples was realized to decrease while the molar volume increased with the more addition of Y2O3. Some theoretical parameters were evaluated for a better understanding of the glass structure such as, glass and oxygen packing densities, average crosslink density, number of bonds per unit volume, bond stretching force and average single bond strength. FT-IR analysis was employed to investigate the existence of different structural borate units and estimating the N4 ratio. The UV–Vis absorbance spectra was measured and employed to estimate the optical band gap energy. The band gap energy was found to firstly decreased with increasing of the Y2O3 content and then revert back to increase in the highest yttrium doped sample. The Urbach energy, refractive index, molar refraction, molar polarizability and optical basicity were also calculated and discussed.

The staphylococcal biofilm protein Aap mediates cell-cell adhesion through mechanically distinct homophilic and lectin interactions.

The accumulation phase of staphylococcal biofilms relies on both the production of an extracellular polysaccharide matrix and the expression of bacterial surface proteins. A prototypical example of such adhesive proteins is the long multidomain protein Aap (accumulation-associated protein) from Staphylococcus epidermidis, which mediates zinc-dependent homophilic interactions between Aap B-repeat regions through molecular forces that have not been investigated yet. Here, we unravel the remarkable mechanical strength of single Aap-Aap homophilic bonds between living bacteria and we demonstrate that intercellular adhesion also involves sugar binding through the lectin domain of the Aap A region. We find that the mechanical force needed to unfold individual β-sheet-rich G5-E domains from the Aap B-repeat regions is very high, ranging from 300 up to 1,000 pN at high loading rates, indicating these are extremely stable. This high mechanostability provides a means to the cells to form highly adhesive and cohesive biofilms capable of sustaining high physiological shear stress. Importantly, we identify a previously undescribed role of Aap in bacterial-bacterial adhesion, that is, heterophilic sugar binding by a specific lectin domain located in the N-terminal A region, which might be important to establish initial contacts between cells before strong homophilic bonds come into play. This study emphasizes the remarkable mechanical and binding properties of Aap as well as its wide diversity of adhesive functions.

Bond Properties of Magnesium Phosphate Cement-Based Engineered Cementitious Composite with Ordinary Concrete.

A magnesium phosphate cement-based engineered cementitious composite (MPC-ECC) was developed using polyvinyl alcohol (PVA) fibers and fly ash. In this study, the bond behavior of MPC-ECC with ordinary concrete was evaluated through single and double shear bond strength tests. The effects of the water to solid mass ratio (W/S), the sand to binder mass ratio (S/B), the molar ratio of MgO to KH2PO4 (M/P), the fly ash content (F), the borax dosage (B), the volume fraction of PVA fibers (Vf), and curing age on the bond behavior of MPC-ECC with ordinary concrete were examined. The results showed that as the W/S increased, the single and double shear bond strengths were gradually reduced. As the S/B increased, the double shear bond strength increased; the single shear bond strength first decreased up to an S/B of 0.1 and then increased. With the increase of M/P, the single and double shear bond strengths increased. With the increase of F, the single shear bond strength first increased up to an F of 30% and then decreased; the double shear bond strength decreased. With the increase of B, the single and double shear bond strengths increased first and then decreased, and their strength reached its maximum at a B of 6%. The increase of Vf improved the single and double shear bond strengths. The research results can provide some technical guidance for repairing concrete structures with MPC-ECC.

Correlation of physical parameters features with optical and radiation shielding properties of heavy glass

In this paper we discussed the optical and radiation shielding properties are strongly dependent on the physical parameter viz; (i) interionic interaction parameter, A(n0), (ii) coordination number, CN, (iii) single bond strength (BM-O) and (iv) optical basicity, Λ(n0) of glasses (95-x) TeO2– 5Ta2O5 -xBi2O3) where x = 5, 10, 15, and 20 in mol %. Furthermore, the various optical parameters viz; linear refractive index, optical absorption coefficient, optical energy gap, Urbach energy, density, oxygen molar volume, nonlinear refractive index, molar refraction, oxygen packing density, reflection loss, molar electronic polarizability of fabricated glasses were estimated. The shielding parameters viz; mass attenuation coefficient, linear attenuation coefficient, half value layer, mean free path, tenth value layer, effective electron number, effective atomic number, atomic and electronic cross sections have been calculated of fabricated glass against a wide range of ionizing energy ranging from 0.015 to 15 MeV. Results showed that increasing the concentration of Bi2O5 from 5 to 20% led to an increase in the linear attenuation coefficient (LAC). Compared with commercially available standards and reported some tellurite glasses to contain Bi2O3 in the literature, the investigated material showed superior performance at energies ranging between 800 keV and 10 MeV. Radiation protection efficiency (PRE) of 70TeO2–5Ta2O5–20Bi2O3 glass varied from 99.9 to 83.9% at low energy from 15 to 200 KeV. Therefore, this glass has a high density, refractive index, and a superior capability of radiation shielding materials at low energy.

Tailoring the structuralism in xBaO·(30–x)Li2O·70B2O3 glasses for highly efficient shields of Gamma radiation and neutrons attenuators

We prepared transparent xBaO·(30–x)Li2O·70B2O3 glasses and investigated their physical properties using UV/vis and radiation shielding. Density and molar volume of the examined glasses increase as BaO content increases. The energy gap and linear refractive index seem to remain stable as BaO concentration increases. These trends are due to the lack in forming NBOs. In these glasses, there is an insulating behavior and the molar refraction increases with increasing BaO content. The single bond strength is almost constant with increasing BaO content which reveals a constancy in polarizability, consequently a constancy in energy gap and refractive index. Numerous criteria were tested to ascertain the glasses’ suitability as radiation shields. The MCNPX code and Phy-X PSD software were used to investigate the gamma shielding potential in the 0.015–15 MeV energy photon range. Glass’s gamma-protective ability increases as the BaO material increases. The BLB30 sample, which contains 30% mol percent BaO, demonstrated the best gamma-ray shielding efficiency. Additionally, the examined glass specimens can be considered a non-toxic alternative for shielding against gamma radiation and neutrons in a variety of nuclear applications.

Predicting the dissolution rate of borosilicate glasses using QSPR analysis based on molecular dynamics simulations

AbstractQuantitative Structure Property Relationship (QSPR) analysis based on molecular dynamics (MD) simulations is a promising approach for establishing the composition‐property relationships of glasses and other materials with complex structures. A series of 20 borosilicate, aluminosilicate, and boroaluminosilicate glasses have been modeled using MD simulations with recently developed effective potentials. Short‐ and medium‐range structures of these glasses were analyzed and, based on the structural information, QSPR analysis of the initial dissolution rates (r0) of these glasses that were measured at 90°C and pH 9 by using various structural descriptors such as percentage of bridging oxygen species, network connectivity, and average ring size. The structural descriptor, Fnet, which contains both energetic information such as single bond strength and structural information such as cation coordination number and Qn distribution, was also used. It was found that while the overall network connectivity, average ring size and Fnet provide reasonable correlations with r0 of studied glasses, Fnet gives the best correlation among the descriptors. For glasses that show incongruent dissolution, it was found that modification of glass compositions to account for preferential release of modifier cations is necessary to achieve best correlations. The findings were discussed with results of recent studies on evaluating the compositional dependence of glass dissolution behavior using the topological‐constraints‐based models.

Effect of Pb/B ion replacement in B2O3.PbO.Fe2O3.Na2O glasses: Optical, magnetic, and fluorescence properties

Abstract Glasses of the formula (70-x) %B2O3. x%PbO.10%Fe2O3.20%Na2O are prepared by the melt quenching technique. Complete amorphous structure is confirmed for the XRD checked glasses. Molar polarizability, optical basicity and refractive index are found to decrease with increasing the mol% of PbO in the glasses. Single bond strength and interaction parameters suggest the transfer from covalent to ionic nature with the increase of the mol% of PbO in the glasses. The increase of the polarizability values of the studied glasses leads to a high optical nonlinear properties of the glasses. Metallization criterion is found to increase from 0.37 to 0.53 with increasing the mol% of PbO. Continuous addition of PbO is found to control the paramagnetic character of the glasses. The absorption and emission characteristics are studied. The system band gap and absorption intensity are found to be tunable. Also, it is found that the glass system under investigation experiences fluorescence characteristics with green color.

Single-cell fluidic force microscopy reveals stress-dependent molecular interactions in yeast mating

Sexual agglutinins of the budding yeast Saccharomyces cerevisiae are proteins mediating cell aggregation during mating. Complementary agglutinins expressed by cells of opposite mating types “a” and “α” bind together to promote agglutination and facilitate fusion of haploid cells. By means of an innovative single-cell manipulation assay combining fluidic force microscopy with force spectroscopy, we unravel the strength of single specific bonds between a- and α-agglutinins (~100 pN) which require pheromone induction. Prolonged cell–cell contact strongly increases adhesion between mating cells, likely resulting from an increased expression of agglutinins. In addition, we highlight the critical role of disulfide bonds of the a-agglutinin and of histidine residue H273 of α-agglutinin. Most interestingly, we find that mechanical tension enhances the interaction strength, pointing to a model where physical stress induces conformational changes in the agglutinins, from a weak-binding folded state, to a strong-binding extended state. Our single-cell technology shows promises for understanding and controlling the complex mechanism of yeast sexuality.

Dielectric properties, polarizability and molar refractive index of some VSrFeZnO glasses

Dielectric properties of a set of glasses having the composition (70-x)%V2O5 - x%ZnO − 10%SrO − 20%FeO is studied in terms of their permittivity and electric modulus. The dielectric data are collected at the frequencies 120, 103, 104 and 105 Hz and in the temperature range 300 − 523 K. The electric moduli are treated with different theoretical models. Good fitting to the experimental data are obtained with Cole–Cole and Davidson–Cole equations. The static relaxation time τ0 values are found to vary between 7.6x10−9 sec and 22.7x10−9 sec, and the parameters α and γ are found to be (α = 0.056 − 0.065) and (γ = 0.94 − 0.95). The calculated optical basicity values are found to decrease with increasing the %ZnO. The molar refractive index is found to be between 2.6 and 3.2. The calculated single bond strength values suggest the transfer of bond nature from the covalent to the ionic form. The obtained third-order nonlinear optical susceptibility χ(3) results and electronic polarizability calculations suggests these glasses to be good nominees for nonlinear optical applications.

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.

The stiffening or softening of nanomaterials determined by a quantitative model

A quantitative model for the size-dependent Young’s modulus Y(D) of nanomaterials is established in this work by considering the modulus of single bond and bond number in nanomaterials. Due to bond relaxation, the single bond strength and it’s elastic modulus are enhanced as size drops, while bond number is decreased. This makes the Young’s moduli of nanomaterials possess different change with size. If compared with bulk Young’s modulus Y0, both the stiffer with Y(D) > Y0 and the softer with Y(D) < Y0 for different nanomaterials are predicted. The corresponding experimental or simulation results show their good consistence with the model predictions, which greatly confirms the reasonability of the established model.

An ab initio study of the valence tautomerism of type B mesoionic rings

The MP2 calculated Gibbs free energies of a series of type B mesoionic rings and their acyclic valence tautomers suggest that in the gas phase the relative stability of the mesoionic ring increases with single bond strength (SS > RNNR > OO). Inclusion of aqueous solvation in the calculations further favours the stability of the mesoionic ring by ∼10–15 kcal mol−1. Replacement of CR groups at ring positions by nitrogen atoms results in a significant increase in the relative stability of the mesoionic ring. Calculations of aromatic stabilization energy (ASE), together with the Bird aromaticity index (I5), suggest that aromaticity decreases with aza substitution and the increase in relative stability is attributable to charge stabilisation by the electronegative nitrogen atoms, which more than compensates for any loss of aromaticity.

Single and dual adhesive bond strength analysis of single lap joint between dissimilar adherends

The emerging trends for joining of aircraft structural parts made up of different materials are essential for structural optimization. Adhesively bonded joints are widely used in the aircraft structural constructions for joining of the similar and dissimilar materials. The bond strength mainly depends on the type of adhesive and its properties. Dual adhesive bonded single lap joint concept is preferred where there is large difference in properties of the two dissimilar adherends and demanding environmental conditions. In this work, Araldite-2015 ductile and AV138 brittle adhesives have been used separately between the dissimilar adherends such as, CFRP and aluminium adherends. In the dual adhesive case, the ductile adhesive Araldite-2015 has been used at the ends of the overlap because of high shear and peel strength, whereas in the middle of the bonded region the brittle adhesive AV138 has been used at different dimensions. The bond strength and corresponding failure patterns have been evaluated. The Digital Image Correlation (DIC) method has been used to monitor the relative displacements between the dissimilar adherends. Finite element analysis (FEA) has been carried-out using ABAQUS software. The variation of peel and shear stresses along the single and dual adhesive bond length have been captured. Comparison of experimental and numerical studies have been carried-out and the results of numerical values are closely matching with the experimental values. From the studies it is found that, the use of dual adhesive helps in increasing the bond strength.

Preparation of Ca2SnO4:Tb3+, R3+ phosphors (R3+ = B3+, Al3+ or Ga3+) and the dependence of their luminescence on R3+ cations

Ca2SnO4:Tb3+ phosphors co-doped by R3+ cations (R3+ = B3+, Al3+, Ga3+) can be prepared by a solid-state reaction. They are fine solid solutions, which have been studied in detail by XRD, photoluminescence spectra, and decay curves. The results show that their luminescence can be effectively improved by co-doping R3+ cations and adding Al3+ cation is superior to that with other two dopants whether in fluorescence or phosphorescence. The concentration quenching effect will weaken their luminescence beyond m = 0.07 when Al3+ cation is co-doped. The distortion of host lattice and change of local crystal field symmetry around Tb3+ due to co-doping R3+ can enhance their fluorescence. The formation and increase of oxygen vacancy (V••O) predominate in improving their phosphorescence, while the single bond strength of R-O also plays an important role.

Effect of 940nm Diode Laser Irradiation on Microtensile Bond Strength of an Etch and Rinse Adhesive (Single Bond 2) to Dentin

Statement of the Problem:Laser can influence bonding mechanism by increasing the penetration depth of adhesive in smear layer. The effect of 940 nm diode laser on microtensile bond strength of adhesive to dentin has not been investigated in previous studies. Purpose:The aim of this study was to evaluate the effect of 940 nm diode laser irradiation on microtensile bond strength of Single Bond 2 to dentin. Materials and Method: Thirty sound premolars extracted for orthodontic reasons were randomly divided into five groups as follows: G1 or control: etching+ Single Bond2 (SB); G2: diode laser (940 nm wavelength, 1W power, continuous mode)+ etching+ SB; G3: etching+ laser irradiation+ SB; G4: etching+ SB+ laser irradiation+ adhesive curing; G5: etching+ laser irradiation+ SB +laser irradiation +adhesive curing. After the bonding procedure, Z250 composite resin was applied on the dentin surface in three layers of 2 mm thickness. After 24 hours of immersion in distilled water at 37°C and thermocycling for 1000 thermal cycles, the teeth were sectioned into 1mm2 sticks. The microtensile bond strength was measured using a universal testing machine. Bond strength (MPs) was analyzed by one-way ANOVA followed by HSD post hoc Tukey’s test (α=0.05). Results:G4 (38.35±8.99) showed the significant highest bond strength compared to other groups (p= 0.000). G5 (25.16±6.14) showed significantly higher bondstrength than the control group (18.85±4.79) (p= 0.032).Bond strength of G2 (23.39±6.07) and G3 (22.85±5.11) groups was the same and similar to that in the control group (p> 0.05). Conclusion: Based on the results of this study, it may be concluded that dentin surface irradiation with 940 nm diode laser after adhesive application and prior to curing can significantly increase the bond strength of composite to dentin.

Quantitative Structure-Property Relationship (QSPR) Analysis of ZrO2-Containing Soda-Lime Borosilicate Glasses.

Quantitative structure-property relationship (QSPR) analysis is a promising approach to correlate structural features with properties of glass materials that lack long-range order and usually have complex structures. By using carefully chosen descriptors based on structural models generated from molecular dynamics (MD) simulations, correlations with properties and insights on glass behaviors can be obtained. Zirconia can significantly alter glass properties including chemical durability, even in a small amount, and hence plays an important role in vitrification of nuclear waste where long-term chemical durability is desired. In this study, borosilicate glasses with the composition of xZrO2-(61 - x)SiO2-17B2O3-18Na2O-4CaO with x = 0, 1, 2, 4, 6, and 8 were simulated using classical MD simulations with the recently developed composition-dependent potentials. Short-range (e.g., bond distance and coordination numbers) and medium-range (e.g., Qn distribution, network connectivity, and ring-size distribution) structural features altered by ZrO2 were obtained and analyzed. The use of a descriptor ( Fnet descriptor) that combines short-range structural characteristics, from MD simulations, and the cation-oxygen single bond strength was found to provide excellent linear correlations with the density and initial dissolution rate of these glasses. The results show that by combining MD simulations and QSPR analysis the composition and structural effect on the properties of complex multicomponent glasses can be elucidated, thus suggesting that this is a promising approach for future glass research and new composition design.