Bond Quality Research Articles

Examining the relationship between maternal childhood abuse history and mother-infant bonding: The mediating roles of postpartum depression and maternal self-efficacy

BackgroundThe detrimental effects of childhood abuse on long-term outcomes are well-known, however few studies have examined these effects in the context of postpartum psychopathology, maternal self-efficacy, and mother-infant bonding quality. ObjectiveThis study aimed to examine the relationship between a maternal childhood abuse experience (i.e., physical, psychological, and sexual) and mother-infant bonding disturbances, and whether this relationship was mediated by postnatal depression symptomatology and maternal self-efficacy. MethodA sample of 191 postpartum women (Mage = 32.88, SD = 4.20) recruited online from the general population completed self-report measures of the constructs of interest. ResultsPostnatal depression symptomatology and maternal self-efficacy were found to fully mediate the relationship between psychological child abuse experience and mother-infant bonding disturbances (β = 0.06, SE = 0.03, 95% CI: 0.01, 0.12). Postnatal depression symptomatology (but not maternal self-efficacy) was an independent mediator between psychological child abuse experience and mother-infant bonding (β = 0.07, SE = 0.03, 95 % CI: 0.01, 0.13). After inclusion of other abuse types as covariates in the analyses, the findings for maternal child physical abuse attenuated to non-significance. Child sexual abuse was not associated with the mediating or outcome variables, highlighting the issue of disclosure despite the anonymous online environment. ConclusionThis study highlights the negative impact of psychological childhood abuse experience on the quality of the mother-infant bond during the postpartum period and potential pathways that underlie this relationship. This study also draws attention to the need to recognize comorbidity of abuse types in research.

Study on Effect of Ultrasonic Vibration on Adhesive-film Bonding of Al/CFRP Alloy Joints

The adhesive film is solid at room temperature, and it is difficult to ensure the adhesion of the adhesive film to the adhered plate during the bonding process, resulting in poor bonding quality and difficult bonding quality control. Due to the need to solve this problem, this study proposed ultrasonic to improve the bonding quality. The ultrasonic mechanism to strengthen the adhesive-film bonded of AL/CFRP (carbon fiber reinforced composites) joints was investigated. The ultrasonic vibration was applied to the bonding area after the adhesive film was attached. A double-lap shear plate test revealed a 59.6% increase in bond strength and a 34.2% increase in bond quality stability. By analyzing the temperature and viscosity of the adhesive film after ultrasonic and observing the surface morphology of the cured joint, it was found that ultrasonic could reduce the film viscosity and improve the adhesive film fluidity. At the same time, the adhesive film was promoted to fill the irregular micro pits on the adherend surface, enhancing the mechanical anchoring effect between the adhesive and the adhered plate and thus improving the bonding quality.

Vacuum-infused thermoplastic fibre-metal laminates – Advances in bonding and recycling

Novel methods for bonding and recycling acrylic fibre-metal laminates are investigated. Interfacial bonding is achieved via a methacrylate-based adhesive film. Short beam shear testing was performed to assess the bond quality in like-for-like comparisons of different test parameters. It is shown that apparent interlaminar shear strength is influenced by the adhesive carrier and the initiator. The latter is corroborated by micrographs showing a transition from adhesive failure to cohesive failure. It is confirmed that the adhesive is dissolved by liquid acrylic resin during infusion. Dissolution is used to debond the fibre-metal interface for recycling.

Impact of printing orientation on inter and intra-layer bonds in 3D printed thermoplastic elastomers: A study using acoustic emission and tensile tests

The use of the Material Extrusion technique with Thermoplastic Elastomers is currently growing because of the large number of benefits of this family of materials. They are processable materials with high flexibility, which makes them very useful, for example, in biomedical applications that require flexible objects with complex geometries. This study aims to characterize a specific polymer, namely polyether-block-amide-based polymer (PEBA), by analyzing its anisotropic behavior in printed samples and investigating the mechanical properties based on different printing orientations. Three orientations (X, Y, and Z) were used to relate the printing orientation to the type of bonds formed in the samples: intra-layer bonds, inter-layer bonds, and the deposited filament. Tensile tests following ASTM D638 were conducted to measure sample rigidity, while Acoustic Emission, an advanced Non-Destructive Technique, was employed to examine the trend of the failure process. The presence of voids was also observed to assess printing quality, which is influenced by the printing orientation and alters the quality of bonds. The results revealed that samples printed horizontally exhibited higher Young’s Modulus values and fewer voids in the inner parts. Vertically printed samples displayed inferior mechanical properties and a greater number of voids. Consequently, the intra-layer yielded better bond formation and minimized voids. Acoustic Emission analysis corroborated these findings by demonstrating distinct energy distribution patterns among the different printing orientations. Hits were concentrated at maximum stresses, primarily observed in the vertically printed samples, which experienced macroscopic failure. Furthermore, this particular specimen exhibited a vertical asymptote near the maximum stress level. The analysis of the energy of Acoustic Emission hits demonstrated a reasonably good fit with the Gutenberg-Richter (GBR) law based on the printing direction.

Influence of the Application Method of Bitumen Emulsion on the Layer Bond

AbstractAsphalt is paved in several layers. A good layer bond between the individual asphalt layers is necessary for a long service life of the asphalt pavement. For many years, bitumen emulsions have been used to bond the layers together in accordance with the requirements. Usually, the emulsion is sprayed and the asphalt layer is paved in two steps. In the first step, the base is sprayed with the bitumen emulsion. In the second step, after the bitumen emulsion has broken, the asphalt is placed. However, paving can also be carried out using a spray paver with an integrated spraying device. In this case, spraying and paving are carried out in one work process. In this study, the influence of both paving methods on the layer bond is investigated. For this purpose, the two methods are simulated in the laboratory and the effect is analysed for different bitumen emulsions (C60 BP4-S; C40 BF5-S) and different spray rates. The aim of the study is to find out the suitability of bitumen emulsions for the spray paver method when paving asphalt wearing courses (4 cm), and to reveal possible damage potentials. It was detected that the amount of water in the bitumen emulsion has a significant impact on the quality of the layer bond. Therefore, the total amount of emulsion applied also has an influence on the layer bond as the amount of water increases with the total amount of emulsion.

Effects of mental health stigma on loneliness, social isolation, and relationships in young people with depression symptoms

BackgroundMajor depressive disorder (MDD) is the most prevalent affective disorder and the leading cause of illness and disability among young people worldwide. Besides being more susceptible to the onset of depression, young people have a higher risk of loneliness, and their personal and social development is impacted by social relationships during this time. It is thought that mental health stigma can undermine both help-seeking and longer-term outcomes for disorders like depression in young people. However, how stigma (i.e., related to depression) might affect young people’s feelings of loneliness, social isolation, and relationships is unclear. Using qualitative research methods, this study aimed to explore the subjective experiences of public and internalized stigma and its effects on loneliness, social isolation, and relationship quality in young people with depression symptoms.MethodsWe carried out in-depth, semi-structured interviews with N = 22 young people aged 17–25 (Mage = 22 years) who reported high symptoms of depression (Mood and Feelings Questionnaire (MFQ) score > 27) (i.e., community sample, N = 9) or had been previously diagnosed with depression by a medical professional (i.e., clinical sample, N = 13). Data were analysed using thematic analysis. We explored the subjective effects of depression stigma on loneliness, social isolation, and relationships.ResultsParticipants described both public stigma (i.e., initiated by others) and internalized stigma (i.e., self-imposed) as disrupting social relationships and eliciting loneliness, isolation, and depressive symptomology. Four main themes about young people's subjective experiences of stigma were identified: 1) Others’ Misunderstanding of Mental Health Disorders and the Impact Misunderstanding has on Relationships; 2) Effects of Stigma on the Self and Wellbeing; 3) Stigma Fosters Secrecy Versus Disclosure; and 4) Stigma Increases Loneliness Driven by Avoidance of Social Contexts.ConclusionsYoung people's accounts revealed a wide range of consequences beyond their depression diagnosis. Participants often felt discriminated against, misunderstood, and judged by others as a result of public stigma; they discussed internalizing these attitudes. They suggested that a lack of understanding from others, for example from their partners, family, and peers, and unreliable and/or absent support systems resulted in increased feelings of loneliness and social isolation and reduced the quality and quantity of relationship formation, social bonds, and interactions. Stigma also reduced their self-esteem and confidence, which in turn fostered secrecy and a reluctance to disclose their depression. Despite depression's stigma, most participants reported having long-term goals and aspirations to reconnect with others. These goals stood in contrast to feeling hopeless and unmotivated during periods of depression. Overall, we reveal how stigma can impact feelings of loneliness, social isolation, and relationships among young people with depression, which could lead to targeted interventions to lessen the impact of stigma in this population.

Ultrasonic inspection during autoclave cure of reflowable-interface composite joints

In structural bonds, the interface between adherend and adhesive is nearly two-dimensional making the interface susceptible to minute quantities of contamination, which can cause weak bonds. Regulatory organizations such as the Federal Aviation Administration (FAA) often require redundant load paths in secondary-bonded primary-structures due to uncertainty in bond performance. To address this issue, the NASA Convergent Aeronautics Solutions (CAS): Adhesive Free Bonding of Composites (AERoBOND) project is investigating reformulated aerospace epoxy-matrix resins to enable reflow and diffusion of the resin at the joint interface during a secondary bonding and cure process that can eliminate the material discontinuity at the interface. Implementing in-situ process monitoring enables assessing the bond quality during processing rather than waiting for post-fabrication mechanical testing to be completed. In this paper, an in-situ ultrasonic inspection system is used to monitor the joining of three composite laminates assembled using the AERoBOND technique. For each panel, the amplitude of the wave reflection at the joint was measured throughout the cure cycle. The results indicate the timing and extent of reflow and cure of the epoxy resin at the joint. Factors indicating end of cure were ascertained and a metric was developed to qualitatively predict acceptable mode-II fracture toughness based on the ultrasonic amplitude at the joint line during cure. In addition, since the inspection system scans an area of the joint, high-resolution localized results can be obtained across the joint.

Ultrasonic Based Testing Method for the Symmetry and Dissymmetry Analysis of the Bonding Quality of a Three-Layer Bonded Structure

Ultrasonic Based Testing Method for the Symmetry and Dissymmetry Analysis of the Bonding Quality of a Three-Layer Bonded Structure

Comparison of Anodic and Au-Au Thermocompression Si-Wafer Bonding Methods for High-Pressure Microcooling Devices.

Silicon-based microchannel technology offers unmatched performance in the cooling of silicon pixel detectors in high-energy physics. Although Si-Si direct bonding, used for the fabrication of cooling plates, also meets the stringent requirements of this application (its high-pressure resistance of ~200 bar, in particular), its use is reported to be a challenging and expensive process. In this study, we evaluated two alternative bonding methods, aiming toward a more cost-effective fabrication process: Si-Glass-Si anodic bonding (AB) with a thin-film glass, and Au-Au thermocompression (TC). The bonding strengths of the two methods were evaluated with destructive pressure burst tests (0-690 bar) on test structures, each made of a 1 × 2 cm2 silicon die etched with a tank and an inlet channel and sealed with a plain silicon die using either the AB or TC bonding. The pressure resistance of the structures was measured to be higher for the TC-sealed samples (max. 690 bar) than for the AB samples (max. 530 bar), but less homogeneous. The failure analysis indicated that the AB structure resistance was limited by the adhesion force of the deposited layers. Nevertheless, both the TC and AB methods provided sufficient bond quality to hold the high pressure required for application in high-energy physics pixel detector cooling.

Detection of “zero-volume” defects in concrete repair systems using impact-echo method

Adhesion in this system is one of the most important factors that affect the reliability and durability of repair. According to the many standards and guidelines, a pull-off test is recommended for assessment of a bond quality in repair systems. However, a growing interest in development of non-destructive techniques (NDT) for evaluation of concrete structures is recently noted. A majority of NDT methods mentioned in EN 1504-10 for repair efficiency assessment are based on propagation of stress waves. The impact echo method is considered as a one of the promising. The literature data confirmed that the “non-zero volume” defects containing air are relatively easy to detect with impact-echo method if they are large enough. It is more complex to detect “zero-volume” defects, e.g dust or any other antiadhesion material. In this work usability of impact-echo for detection of “zero-volume” defects in repair systems is discussed.

Quality assessment of adhesive joints using third harmonics of fundamental shear horizontal wave mode

This study aims to investigate the bond quality of aluminum–epoxy–aluminum tri-layer bonds using nonlinear ultrasonics. An experimental methodology was developed in which the tri-layer bonds with different interface qualities were inspected using the fundamental shear horizontal guided wave mode (SH0). An in-house developed magnetostrictive transducer assembly was used to excite the SH0 wave mode in the bonded samples. The harmonic generation of the SH0 wave mode was confirmed using dispersion curves overlaid on short-time Fourier transform (STFT) and frequency–wavenumber plots. The sensitivity of the third harmonics to the interface quality of the bonds was estimated using a relative nonlinearity parameter ([Formula: see text]). In this work, the mean [Formula: see text] for the non-sandblasted bond is found to be 70% more than that of the sandblasted sample, which shows the sensitivity of the third-harmonic generation to the interfacial degradation. The analysis shows that the technique can be implemented for a quick and early inspection of the bonded samples for their bond quality.

Classification of adhesive bonding between thermoplastic composites using ultrasonic testing aided by machine learning

Adhesive bonding is widely used for joining light weight structures and surface preparation methods play a significant role in improving the bonding quality. Bond quality assessment of thermoplastic composites can be challenging due to the highly inhomogeneous structure. This article explores the use of ultrasonic testing to nondestructively characterize the bond state between thermoplastic composites with different surface preparation methods. Classification of bond states was carried out using a physics-based statistical method and machine learning based method. The results suggest that machine learning methods show a higher classification accuracy. The ultrasonics results were validated using destructive lap-shear testing.

Comparison of asphalt emulsion-based chip seal and hot rubber asphalt-based chip seal

The use of asphalt emulsion chip seal and hot rubber chip seal as pavement preservation techniques has been gaining popularity. This study aims to compare the laboratory performance of asphalt emulsion and hot rubber asphalt used in chip seal applications. Interlayer shear strength (ISS) and interlayer tensile strength (ITS) tests were designed to evaluate the bond quality of the chip seal samples prepared for both materials. The sweep test was used to estimate the aggregate loss of the chip seal on the asphalt pavement. The universal testing machines were used to evaluate the deterioration of the ISS and ITS values under cyclic load conditions, while the tensile and shear bond properties of chip seals under wet-freeze conditions were evaluated using freeze-thaw cycles. Results showed while both materials experienced a decline in their ISS and ITS values following repeated cycles of load and freeze-thaw, the hot rubber chip seal demonstrated significantly higher ISS and ITS values than the asphalt emulsion chip seal (48–111% and 36–102%, respectively). Moreover, the hot rubber chip seal exhibited better performance in terms of aggregate retention and cohesive strength. The aggregate gradation would affect the aggregate retention and cohesive strength. Nonetheless, both treatments are deemed acceptable for pavement maintenance. The weak bond between hot rubber asphalt or asphalt emulsion and aggregate could be attributed to cyclic load and freeze-thaw conditions.

Effects of the Surface Roughness of Six Wood Species for Furniture Production on the Wettability and Bonding Quality of Coating

Wood surface roughness, surface free energy (SFE), wettability, and bonding quality for water-based acrylic coatings were investigated. The samples tested in this study included Pinus radiata, Pinus sylvestris, Larch, Hemp oak, Catalpa tree, and Camphor. Sandpaper with grits of 180, 240, 320, 400, and 500 was utilized to sand wood surfaces. The van OSS-Chaudhury-Good equation (vOCG) was used to calculate the SFE values. The modified model (M-D) was used to calculate the wettability based on the contact angle change rate (K value). The higher the K value, the faster the contact angle approaches equilibrium. A cross-cut test was used to evaluate the coating’s bonding quality. The anatomical structure of wood has an impact on the roughness of hardwood. The equilibrium contact angle is influenced by the wood species and sandpaper grit size. Sanding can make the surface of wood more wettable. Radiata pine that had been sanded to 180 grit had the highest SFE value. After finishing with waterborne acrylic, hardwood had a slightly better coating adhesion than softwood. Hemp oak wood had the lowest coating adhesion (0.6) and the highest K value (0.82). The best bonding quality (0.4) was supplied by the camphor wood with the lowest K value (0.13). Wettability in terms of K values was a good indication of determining the bonding quality of the water-based acrylic coatings.

Contemporary trends on global corporate ESG bond market

Aim. The presented study aims to identify current trends in the global corporate bond market with environmental, social, and management objectives of the issuance of ESG bond and to assess the prospects for their development.Tasks. The author analyzes the segments of the global ESG bond market; determines the causes of the emerging trends and their impact on the state of global ESG financing.Methods. This study uses general scientific methods of cognition, in particular induction and deduction, synthesis, comparative and retrospective analysis. The fundamental regulatory documents of ESG bond taxonomy are investigated, and statistics from representative sources are analyzed. The latter include International Capital Market Association, SPGlobal, Barclays, Goldman Sachs, Refinitiv, and Climate Bond Initiative.Results. Based on the conducted research, the reasons for the active growth in 2021 and the slowdown in the development of the global ESG bond market in 2022 are established, and its short-term prospects are assessed. The prospects are systematized according to ESG bond varieties. Analysis of the mutual influence of global trends on the state of the global ESG bond market indicates the prevalence of external factors.Conclusions. According to the results of the analysis, the ESG bond toolkit seems to be investment-relevant. In 2022, major discussions regarding global ESG debt revolved around market quality and potential greenwashing. Intensive measures are taken in these areas at the macro and micro levels. The volume of ESG bond issuance in 2023 should be restored as interest rates in developed countries stabilize and global inflation rates decrease. Experts remain positive in their expectations and forecasts for 2023, but the quality of green bond and bond related to sustainable development is alarming.

Effect of the Annealing Process on Cu Bonding Quality Using Ag Nanolayer

Effect of the Annealing Process on Cu Bonding Quality Using Ag Nanolayer

Influence of knots on the adhesion of wood from young Eucalyptus grandis plantations

ABSTRACT The structural use of wood from young trees requires gluing smaller timber pieces to form large elements. In young Eucalyptus timber of structural dimensions, knots do not significantly diminish the mechanical properties, yet their influence on wood adhesion has not been widely studied. Therefore, the aim of the study was to assess the influence of knots on the bond quality of face-glued wood from young E. grandis. Wood from seven-year-old E. grandis trees was tested in shear on the bond-line (polyurethane adhesive) using paired samples of knot-containing and clear wood samples. Knot features did not correlate with shear strength or wood failure percentage. Knot-containing samples had a lower percentage of wood failure (5.8%), but the same shear strength as clear wood samples. Below a wood density of 650 kg m−3, clear and knot-containing wood behaved similarly, but above this value, knots influenced wood adhesion negatively. By simulating glulam beams with high-density wood on the outer lamellas, it was possible to show that shear stress on those bond-lines is lower than the minimum shear strength observed on dense knot samples. Hence, lower adhesion caused by knots on denser wood probably does not represent a significant problem for glued laminated products from young Eucalyptus grandis trees.

Study on explosive welding of Cu/steel composite pipe under local water environment

AbstractIn order to improve the energy utilization rate and the bond quality of explosive welding, the local water environment method is used in present study. In this paper, several groups of high‐quality Cu/Steel explosive composite pipes are prepared under local water environment. Optical microscope and mechanical property tests are conducted to analyze samples microstructure and mechanical properties. The results show that the waveform dimension of Cu/Steel bonding interface has a positive correlation with explosive layer thickness, and the miniature wavy bonding interface with the highest bonding quality is obtained by using the local water environment method. Compared with the traditional charge method, the consumption of explosives for the local water environment charge method is decreased about 60 % in the same case of experimental conditions. The local water enviroment method solves the problem of ablation damage at the contact surface between metal and explosives, and effectively reduces the diameter expansion phenomenon and end damage caused by boundary effect in the welding process. Through mechanical property tests, it was found that the yield strengths and compressive strengths of Cu/Steel specimens which created by the local water environment method are positively correlated with the explosive thickness.

Effects of type and distribution of clay minerals on the physico-chemical and geomechanical properties of engineered porous rocks

The study of the properties of engineered rocks is of great importance to researchers in engineering sciences such as petroleum, mining, and civil engineering owing to their wide application in these fields. In the present study, a physico-chemical and geomechanical investigation was carried out on the effects of different clay minerals on porous rocks. Various chemical products formed during chemical interactions between cement, clay minerals, and water can change the pore structure and thus the rock characteristics. The results of the current study showed that increasing the clay content could remarkably reduce the porosity and permeability of the rock by an average of 86% and 6.76%, respectively. In this regard, samples containing kaolinite were further influenced due to their new pore structure. Moreover, a power relationship was found between sonic velocity and porosity, which can be used to predict rock properties. Chemical analysis indicated an amplification in quantities of chemical products, particularly calcium silicate hydrate and portlandite, due to an increase in clay content. The impacts of porosity and cementation quality as two main factors on rock strength have also been studied. The outcomes revealed that a reduction in porosity could compensate for detrimental effects of poor bond quality and consequently improved UCS by up to 30% in samples containing kaolinite, while decreasing the degree of cementation prevailed over the porosity reduction in specimens including illite and resulted in a 14% decrease in UCS. The effects of porosity and bond quality on UCS would cancel each other out in samples containing bentonite. It is worth noting that when it comes to changes in geomechanical characteristics, the dominant factor (i.e., porosity reduction or cementation quality) determines the ultimate effect of clay minerals on the properties of engineered porous rocks.

Photodegradation risk evaluation of polyurethane gluelines in wood products by infrared spectroscopy and mechanical tests

During outdoor use, glued wood products are exposed to rather harsh conditions, which involve moisture and temperature fluctuations, attacks by microorganism, UV radiation etc. For some risks, the effect on glued wood products are already known, however less investigated are the risks concerning UV radiation. It has been established that weathering affects only the surface of the wood without influencing the mechanical properties. However, polyurethanes are known to undergo more significant degradation with structural changes, strength reduction and surface erosion. The objective of the study was to investigate whether photodegradation caused by UV irradiation can impair the bond quality of glued wood products bonded with one-component polyurethane adhesives. In the study, considerable attention was attributed to the investigation of the chemical changes by FTIR methods focusing on the differences as well as normalisation possibilities of the spectra. The results showed that UV significantly degraded the chemical structure and mechanical properties of the one-component polyurethane films as well as introduced a number of microcracks in the gluelines. Despite that, glued wood products after UV irradiation showed only minor or none at all reduction in the bond quality characterised by wood failure percentage. The only identified aspect that had some effect was the thickness of glueline, which should be kept at minimum. The chemical analysis revealed two stable bands, which could be used for normalisation of polyurethanes FTIR spectra during weathering investigations. The corresponding bands are attributed to the aromatic and isocyanurate ring structures.