Transverse Bond Research Articles

Kink effect on the lattice properties of one-dimensional carbyne nanocrystals under high temperature

Carbyne nanocrystal (CN), as a kind of one-dimensional (1D) sp-hybridized carbon allotrope, has attracted much attention due to its excellent optical and transport properties. However, the lattice properties of 1D CNs under high temperature remain unclear. In our work, we investigate the stability and lattice properties of 1DCNs based on the atomic-bond-relaxation (ABR) approach and first-principles calculations. We find the change of transverse vibration frequencies and bond kinks induced by the thermal effect plays a significant role in the mechanical properties of 1D CNs. We establish a relationship between kink angle and phonon vibration modes, giving a deep inside into high frequency and low-frequency vibration behavior of 1D CNs. Our results indicate the phonon vibration modes modulated by kinks under applied temperatures can lead to a negative thermal expansion behavior in the axial direction of 1D CNs, suggesting an effective way to control the thermal properties of 1D CNs for practical applications.

A conjugated bond-based peridynamic model for laminated composite materials

The bond-based peridynamic (BB-PD) theory is inadequate in describing the four independent engineering material constants of composite lamina, which results in fixed values its Poisson's ratios and shear moduli. This study presents a novel lamina conjugated BB-PD model encompasses not only the fiber bond and matrix bond, but also the transverse bond and conjugated bond pair. By defining these four basic PD bonds, the improved conjugated BB-PD model can overcome the restriction of material properties. The determination of the four basic PD micro-modulus parameters is achieved through the utilization of the equivalent relationship of strain energy density. In addition, the lamina conjugated BB-PD model is extended to deal with composite laminates with different stacking sequences. The present study validates the accuracy and applicability of the conjugated BB-PD model for composite materials by conducting simulations of the elastic deformation and progressive damage behavior of unidirectional laminae and laminates. Moreover, the proposed model provides an elucidation of the damage modes and failure mechanisms of laminated composite materials subjected to uniaxial loading.

Multiscale Mechanics of Thermal Gradient Coupled Graphene Fracture: A Molecular Dynamics Study

The thermo-mechanical coupling mechanism of graphene fracture under thermal gradients possesses rich applications whereas is hard to study due to its coupled non-equilibrium nature. We employ non-equilibrium molecular dynamics to study the fracture of graphene by applying a fixed strain rate under different thermal gradients by employing different potential fields. It is found that for AIREBO and AIREBO-M, the fracture stresses do not strictly follow the positive correlations with the initial crack length. Strain-hardening effects are observed for “REBO-based” potential models of small initial defects, which is interpreted as blunting effect observed for porous graphene. The temperature gradients are observed to not show clear relations with the fracture stresses and crack propagation dynamics. Quantized fracture mechanics verifies our molecular dynamics calculations. We provide a unique perspective that the transverse bond forces share the loading to account for the nonlinear increase of fracture stress with shorter crack length. Anomalous kinetic energy transportation along crack tips is observed for “REBO-based” potential models, which we attribute to the high interatomic attractions in the potential models. The fractures are honored to be more “brittle-liked” carried out using machine learning interatomic potential (MLIP), yet incapable of simulating post fracture dynamical behaviors. The mechanical responses using MLIP are observed to be not related to temperature gradients. The temperature configuration of equilibration simulation employing the dropout uncertainty neural network potential with a dropout rate of 0.1 is reported to be the most accurate compared with the rest. This work is expected to inspire further investigation of non-equilibrium dynamics in graphene with practical applications in various engineering fields.

Winning Strategy toward Acentric Crystals: Transverse Dipole Moment Molecules

Imines obtained by condensation of 4-hydroxybenzohydrazide with carbonyl compounds are a rare example of non-chiral compounds showing a remarkable tendency to crystallize in acentric and polar space groups, as we underlined in a previous study of imines obtained by condensation with aliphatic ketones. Here, we present an extensive study of imines obtained by condensation with aromatic aldehydes and demonstrate that over a representative set of 60 crystal structures, the overall occurrence of acentric phases in this class of compounds is 47%. This figure is remarkably higher than the overall 22% frequency of acentric structures in the Cambridge Structural Database and pinpoints a successful strategy toward the synthesis of acentric crystals. In the crystal structures of the acentric imines, complex chains of H-bonded molecules are generally present, with formation of 2D H-bonded networks, similar to other classes of compounds described in the literature with a propensity to form acentric crystals. Another reason for the high success in achieving acentric and polar structures in this class of compounds can be related to the presence of strong transverse bond dipole moments. This feature allows a polar packing of the long molecular axes while keeping the bond dipole moments antiparallel.

Bond-Slip Performance between High-Strength Steel Wire Rope Meshes and Engineered Cementitious Composites

Engineered cementitious composites (ECC) are distinguished by ultrahigh ductility and multiple cracking. High-strength stainless steel wire rope (HSSSWR) meshes have been successfully applied to strengthening existing structures. Taking advantage of both ECC and HSSSWR meshes, HSSSWR mesh–reinforced ECC promises to be an innovative strengthening material for significantly improving overall performance of existing structures. In order to capture the bond performance between HSSSWR meshes and ECC, direct pull-out tests on HSSSWR meshes embedded in ECC were performed considering the effects of spacing of transverse wire ropes, bond length, and nominal diameter of HSSSWR. The influence laws of the considered factors on the bond behavior between HSSSWR meshes and ECC were investigated. The failure characteristics and bond-slip relationship between HSSSWR meshes and ECC were revealed through analyses of experimental results. A bond-slip model was proposed to predict the bond-slip behavior of HSSSWR meshes in ECC, which was verified to be acceptable by comparing it with test results.

Efficient sensitizer-supported electron beam irradiation induced crosslinking of polyvinylidene fluoride for shape memory applications

Polyvinylidene fluoride (PVDF) preferentially crosslinks upon exposure to ionizing electron beam irradiation, leading to substantial changes in its physicomechanical and thermophysical properties. However, low dose electron beam irradiation produces inefficient crosslinking in pure PVDF while high dose irradiation tends to induce the concomitant process of transverse bond degradation. This has been addressed by incorporating a sensitizer into PVDF to increase crosslinking efficiency under low dose irradiation. However, conventional sensitizers typically suffer from self-polymerization and the release of toxic volatile gases at high temperature, which diminishes the crosslinking efficiency and is toxic. This issue is addressed here via a series of well-designed bismaleimide (BMI) sensitizers and incorporating these into PVDF films for facilitating chemical crosslinking reactions under low electron beam irradiation doses. Analysis indicates that the sensitizing action of the proposed BMI sensitizers may be due to the formation of transverse bonds between vinylene groups and PVDF chains. Versus conventional triallyl isocyanurate and trimethylolpropane triacrylate sensitizers, the proposed BMI sensitizers facilitate high radiation crosslinking efficiency and exhibit good compatibility. Accordingly, the proposed sensitizers leading to irradiated PVDF films with outstanding thermomechanical performance and shape memory functionality.

Impact of corrosion on risk assessment of shear-critical and short lap-spliced bridges

Increasing corrosion in aging reinforced concrete structures is increasing their vulnerability to failures. This is particularly true for bridges with low-ductility columns, including shear-critical columns and columns with short lap splices. This paper presents a methodology to assess the impact of corrosion on performance of these structures. The combined analytical and numerical modeling of shear-critical and lap-spliced columns is detailed, and outcomes are verified with previous experimental test data. Corrosion effects are accounted for through reduction of longitudinal and transverse reinforcement and bond deterioration between the steel and concrete through corrosion-induced cracking. The impact of corrosion on risk is assessed through conducting fragility analyses. Results quantify the increase in failure probabilities of these structures, measured by increasing probabilities of exceeding defined damage states, with increasing levels of corrosion. Corrosion is found to have a larger impact on increasing probabilities of exceeding more severe damage states. Twenty percent mass loss of reinforcement increases the probability of exceeding the complete damage state by up to 49% and 34% for a shear-critical and lap-spliced column, respectively. The effect is more pronounced at intermediate loading intensities, where there is uncertainty about the performance of the structure. Comparing between failure modes, bridges with columns of short lap splice are more vulnerable to collapse under the same degree of corrosion compared with shear-critical columns.

Influence of Silver Nanoparticles on the Specific Properties of Acrylic Resin for Ocular Prosthesis

Scleral acrylic resin is widely used to synthesize ocular prosthesis. However, the properties of this material change over time, thus requiring the prosthesis to be refabricated. Many studies were conducted to improve these properties by reinforcing this material with nanoparticles. This study aims to evaluate the effect of silver nanoparticle powder on the mechanical properties (transverse flexural strength, impact strength, shear bond strength, surface microhardness, and surface roughness) of scleral acrylic resin used for ocular prostheses. Two concentrations were selected from the pilot study and evaluated for their effects on scleral acrylic resin properties. According to the pilot study, 0.01 and 0.02wt% AgNPs powder improved the transverse flexural strength, microhardness, and surface roughness compared with other percentages. The specimens in the main study were divided into (3) main groups, (50) specimens without additives (control group A), (50) experimental specimens (with 0.01wt% AgNPs group B), and (50) experimental specimens (with 0.02 wt% AgNPs group C). Each group was subdivided into (5) equal subgroups depending on the tests used. The data were studied using one way ANOVA and post hoc LSD test. At 0.01 wt% AgNPs addition, the mean values of transverse flexural strength insignificantly increased (p> 0.05), and those of impact strength and shear bond strength significantly increased (p< 0.05) compared with those of the control group. At 0.02 wt% AgNPs addition (group C), the mean value of transverse flexural strength significantly increased (p< 0.05), that of impact strength insignificantly increased (p> 0.05), and that of shear bond strength increased with high significance (p< 0.01) compared with those of the control group. Group C showed insignificant increase in the mean values of transverse flexural strength, impact strength, and shear bond strength (p. 0.05) compared with group B. The scleral acrylic resin added with 0.01 and 0.02 wt% AgNPs showed insignificant increase in microhardness and insignificant decrease in surface roughness. The addition of AgNPs powder in both concentrations improved the mechanical properties of scleral acrylic resin used for ocular prostheses.

Effect of certain chemical surface treatments on repair bond strength of some denture base materials

Fracture of different types of acrylic denture base is a common problem associated with dental prosthesis. Studies suggested that the repair strength may be improved by several means including surface treatment with chemical agents. The aim of the study was to evaluate the effect of surface treatment with acrybond-bonding agent and monomer on fractured denture base in respect to transverse, tensile and shear bond strength and evaluation of the mode of failure by light microscope. Materials and methods: Two hundred seventy specimens were prepared and divided into 3 groups according to the material used (regular conventional, rapid simplified and high impact) heat cure acrylic. The specimen in each groups were prepared specifically according to testing (tensile, transverse and shear bond strength). All the specimens were stored in 37°C for 28days before fracture then the specimens in each test were divided into 3 groups according to surface treatment (control-without surface treatment, monomer(MMA) group and acrybond (MMA with acetone ))group. The specimens repaired with cold cure acrylic using Ivomet; then stored in distill water at 37°C for 2days before testing. GEFRA universal testing machine was used and final load at fracture was recorded. Results: monomer and acrybond group exhibited higher bond strength than control group. Conclusion: the type of denture base affect the value of bond strength and the use of monomer or acrybond resulted in higher bond strength than untreated surface.

Comparative Evaluation of Heat-Polymerized and Auto-Polymerized Soft Liners with Regard to Transverse Bond Strength, Peel Bond Strength and Water Sorption: An in vitro Study

ABSTRACT Purpose This is an in vitro study for comparative evaluation of transverse bond strength, peel bond strength and water sorption properties between heat polymerized and auto-polymerized resins. Materials and methods Two denture soft liners (Molloplast-B, Coe-Soft) were investigated. A total number of 60 specimens were used. Twenty specimens were used for evaluation of each physical property of soft liner. For transverse bond strength, ten specimens (64 ⨯ 2.5 ⨯ 10 mm) of each liner were made by processing the denture liners with heat cure polymethyl methacrylate (Meliodent). All specimens for transverse bond strength were conducted on samples immersed in distilled water at 37°C for 50 hours by using three-point transverse flexural tests in a Lloyd's Universal Testing Machine and transverse bond strength was calculated based on the maximum load, span length, breadth and thickness. Another set of ten specimens of (75 ⨯ 25 ⨯ 3 mm) of each denture liner were bonded over 25 mm of heat cure PMMA and separated over the remaining 50 mm of acrylic plate to estimate the peel bond strength. The peel bond strength were conducted on specimens which were dried at room temperature for 48 hours and tested at 21 1 ± C in a Lloyd's testing machine that was linked to an IBM Compatible Computer. The specimens were deformed with a cross head speed of 5 mm/minute according to ASTMD-903 and peel bond strength was calculated when peel angle was 180°. For water sorption tests, ten disc shaped samples of each liner of 50 mm in diameter and 0.5 mm in thickness were fabricated. After polymerization of the liners, the samples were then stored in distilled water at 37°C for 7 days. After one week, excess moisture was removed and each sample was weighed using electronic weighing machine. Results The transverse bond strength of Molloplast-B and Coe-Soft were almost similar and did not show any significant difference in their values. But, there is a significant decrease in the peel bond strength and water sorption property of Molloplast-B and Coe-Soft. Conclusion The reason for transverse bond strength results being similar for both the liners is because they were polymerized chemically with the denture base resins and this chemical affinity could have made its bond strength almost equal. Since, there is a decrease in the peel bond strength of Molloplast-B, the chances of stripping of the liner at the flanges of the denture is minimal. The decrease in water sorption of Molloplast-B can be expected to retain the bond with the denture and sustain the resilience property of the material for a longer time. How to cite this article Krishnappan PL, Jaiesh R, Swa- minathan TN. Comparative Evaluation of Heat-Polymerized and Auto-Polymerized Soft Liners with Regard to Transverse Bond Strength, Peel Bond Strength and Water Sorption: An in vitro Study. Int J Prosthodont Restor Dent 2014;4(3):61-67.

Evaluation of adhesion of reline resins to the thermoplastic denture base resin for non-metal clasp denture

This study aimed to evaluate the tensile and transverse bond strength of chairside reline resins (Tokuyama Rebase II, Mild Rebaron LC) to a thermoplastic acrylic resin (Acrytone) used for non metal clasp denture. The results were compared with those of a conventional heat polymerized acrylic resin (Paladent 20) and a thermoplastic polyamide resin (Biotone). The failure sites were examined by scanning electron microscopy to evaluate the mode of failure. As results, the bond strength of reline resins to a thermoplastic acrylic resin was similar to the value of a conventional heat polymerized acrylic resin. However, thermoplastic polyamide resin showed the lowest value. The results of this study indicated that a thermoplastic acrylic resin for non metal clasps denture allows chairside reline and repair. It was also found that the light-polymerized reline resin had better bond strength than the autopolymerizing reline resin in relining for a conventional heat polymerized acrylic resin and a thermoplastic acrylic resin.

Evaluation of transverse and tensile bond strength of repaired nylon denture base material by heat, cold and visible light cure acrylic resin

Denture fracture is one of the most common problems encountered by the patients and prosthodontists. The objective of present study was to evaluate the transverse strength of nylon denture base resin repaired by using conventional heat polymerized, autopolymerized and visible light cure {VLC} resins, surface treatment that used for repair and adjustment of insufficient nylon denture bases and in case of addition of artificial teeth. As these corrective procedures are common chair side procedures in dental clinic. Materials and methods: One hundred twenty nylon specimens were prepared by using metal patterns with dimension of (65x10x2.5 mm) length, width, and thickness respectively for transverse strength test while for tensile bond strength a dumbbell-shaped with measurement (65x12.5x25mm) length, width, and thickness respectively were flasked with stone. The nylon specimens were molded by reflasked with dental stone that used as an index for these specimens in the repair procedure and repaired with 45 degree bevel joint by using metal holding device. The two parts of nylon specimen to be repaired were realigned in its repair index and adhere with special adhesive material to stabilize the combination during repair procedure. The dough of heat and cold cure resin was packed into the joint and then cured. The specimen repaired with cold cure resin was placed in the Ivomat containing water at (40°C) and pressure (30IB/inch²) for 15 minutes. The specimen repaired with {VLC} was placed in the light cure unit for 4 minutes following manufacturer's instruction. The fractured nylon specimens were divided according to the type of repaired materials into (40) specimens received heat cure acrylic and the (40) specimens received cold cure acrylic and the other 40 specimens received {VLCR}. Each 40 specimens were subdivided according to the type of surface treatment received into 20 specimens were treated with coarse stone bur (control), 20 specimens were treated with combination of coarse stone bur and monomer of the heat cure acrylic. After that the specimens were subjected to transverse {Tr} and tensile bond {TB} strength tests. For each test 10 specimens. Results and conclusions: This study showed that specimens treated with combination of coarse stone bur and monomer of the acrylic (heat, cold or VL cure) had the highest transverse and tensile strength values, followed by the specimens treated with coarse stone bur. The results showed that the specimens repaired with heat cure acrylic had transverse and tensile strength values higher than the specimens repaired with cold and VL cure acrylic when compared between subgroups of heat, cold and VL cure acrylic that received the same treatments.

Evaluation of Transverse and Tensile Bond Strength of Repaired Nylon Denture Base Material by Heat , Cold and Visible Light Cure Acrylic Resin

Evaluation of Transverse and Tensile Bond Strength of Repaired Nylon Denture Base Material by Heat , Cold and Visible Light Cure Acrylic Resin

Out-of-Plane Seismic Capacity of Masonry Depending on Wall Section Morphology

To what extent does a wall subjected to out-of-plane seismic action behave monolithically and fail by overturning or, conversely, split into separate leaves? How much does the workmanship—the set of construction specifications that historical treatises collect under the definition of “rule of art”—influence the structural behaviour of the wall? These research topics have proved highly significant in the recent seismic events, but yet remain insufficiently known and handled without the appropriate analysis tools. In this article, the dependence of the out-of-plane seismic capacity of masonry walls on the morphology of the wall section is investigated starting from real masonry sections, surveyed from historic buildings, which are modelled using the distinct element method. The seismic capacity is estimated by pushover analyses with uniform increasing horizontal forces and dynamic analyses under acceleration pulses. The results highlight the effective reduction in strength and displacement capacity of masonry sections depending on the transverse bond provided by stones.

Effects of the bond dilution on the phase diagrams of a spin-1 transverse Ising model with crystal field interaction on a honeycomb lattice

A bond diluted spin-1 Ising model with crystal and transverse field interactions is examined for honeycomb lattice by introducing an effective field approximation that takes into account the correlations between different spins that emerge when expanding the identities. The effects of the crystal field as well as the transverse field and dilution on the phase diagrams and order parameter mz are discussed in detail. A number of interesting and unusual phenomena such as reentrant phenomena and three successive phase transitions originating from the crystal field as well as the transverse field and bond dilution have been found.

Bonding and magnetism in nanosized graphene molecules: Singlet states of zigzag edged hexangulenes C6m2H6m(m=2,3,…,10)

A novel molecular phenomenon is predicted on the basis of trends identified in an ab initio density functional theory study of the electronic and geometric structure of the hexagonal shaped zigzag edged graphene hydrocarbon molecules C(6m(2) )H(6m)(m=2,...,10). Electrons in the interior organize to form a graphene core that grows with edge size m. Electrons in the highest occupied molecular orbital levels, localized primarily on the perimeter carbons, polarize the interior atoms with a intensity that decays rapidly with distance from the perimeter. Three distinctive bond length patterns emerge: (i) a central graphene core that grows with size m; (ii) shape-similar transverse and radial bond length patterns on interior rows close to the edges; and (iii) quinoidal bonds radiating from each apex that link adjacent edges. Concomitant with these changes are: (i) a monotonic decrease in atomic charge from center to perimeter and (ii) relegation of spin in diradical states to the outer atomic rows of the bipartite lattice.

Seismic Rehabilitation of Reinforced Concrete Frame Interior Beam-Column Joints with FRP Composites

An experimental research program is described regarding the use of externally applied carbon fiber-reinforced plastic (CFRP) jackets for seismic rehabilitation of reinforced concrete interior beam-column joints, which were designed for gravity loads. The joints had steel reinforcement details that are known to be inadequate by current seismic codes in terms of joint shear capacity due to the absence of transverse steel hoops and bond capacity of beam bottom steel reinforcing bars at the joint. Lap splicing of beam bottom steel reinforcement at the joint using externally applied longitudinal CFRP composite laminates is investigated. Improvement of joint shear capacity using diagonal CFRP composite laminates is another strengthening scheme employed. Concrete crack widths for the as-built specimens and the extent of CFRP delamination for the rehabilitated specimens at various drift ratios are reported. The test results indicate that CFRP jackets are an effective rehabilitation measure for improving the seismic performance of existing beam-column joints with inadequate seismic details in terms of increased joint shear strength and inelastic rotation capacity. In addition, CFRP laminates are effective rehabilitation measures for overcoming problems associated with beam bottom steel bars that have inadequate embedment into the beam-column joints.

Effect of chemical surface treatments and repair material on transverse strength of repaired acrylic denture resin

This study was performed to evaluate the transverse strength of a denture base resin (H), repaired with an autopolymerizing acrylic resin (A) or a visible light-curing (VLC) resin (T) following the use of three chemical solvents: methyl methacrylate monomer, aceton or chloroform. Eighty specimens (65.0 x 10.0 x 3.3 mm) of H were fabricated and stored in distilled water at 37 degrees C for seven days. Specimens were divided into eight equal groups of 10. In each group, specimens were sectioned in the middle to create a 10 mm gap. Two groups served as controls and had no surface treatment. They were repaired with A or T materials. In the remaining six experimental groups, specimen surfaces were treated with ac for 30 sec or mma for 180 sec or ch for 5 sec. Then A or T material was placed on the treated surfaces, using the same preparation molds. After seven days' storage at 37 degrees C, the transverse bond strength (MPa) of the specimens was measured using a three-point bending test. A two-way ANOVA and a Tukey HSD were performed to identify significant differences ( P < 0.05). The nature of the failures was noted as adhesive, cohesive or mixed. Significant differences were found between the controls and experimental groups ( P < 0.05). In the control groups, repair with A showed significantly higher strength (60.3 MPa) than those repaired with T (51.3 MPa). Mean transverse strength of experimental specimens repaired with A was (75.06 MPa) which was significantly greater than those repaired with T (67.9 MPa). Although surface treatment increased repair strength, no significant differences were detected between the effects of the chemical etchants. The autopolymerizing resin exhibited significantly higher repair strength than VLC resin. The transverse strength of the repaired specimens was increased significantly after chemical treatments.

The importance of nonrecurrent laryngeal nerve in thyroid surgery

To investigate the anatomic variation of nonrecurrent laryngeal nerve (NRLN) and its surgical identification and prevention during thyroidectomy. The database of 5 NRLN cases was analyzed to investigate the difference of operative maneuvers and procedures. All 5 NRLN were located in the right side. Two cases were found have vocal cord paralysis and 1 case recovered in 3 cases who have NRLN injures. Any transverse bond should not be cut between vascular and laryngeal except middle thyroid vein. Recurrent laryngeal nerve (RLN) should be dissected during thyroid excision. Cervical pneumogastric nerve should be systematic dissected to detect whether RNLN is exist, if RLN is not exist in the same side.

Temperature-Dependent Signatures of Coherent Vibrational Openings in DNA

We report numerical simulations of the contribution of the transverse hydrogen bond stretching vibrations in the dynamic structure factor of a DNA sequence. We apply a simple nonlinear dynamical model to a finite segment of the bacteriophage T7 core promoter DNA. The temperature dependence of the dynamic structure factor is investigated. A distinct feature is identified and attributed to coherent localized thermal openings (hot-spots) due to nonlinearity combined with sequence specificity. We present the variation of the position and the width of the corresponding dynamic structure factor feature with temperature. Finally, a strong deviation of the Debye−Waller factor from the usual harmonic form is evaluated.