Snap-through Crack Propagation in Architected Bonded Interfaces Analyzed Using a Mechanoluminescent SAO/E Coating.

We investigate the mechanics of crack propagation in architected adhesive joints whose adherends are inspired to the base plate of the barnacle Amphibalanus (=Balanus) amphitrite, and feature an array of buried hollow cylindrical channels located perpendicularly to the direction of crack growth. Selective laser sintering is used to obtain the adherends that are subsequently bonded in the double cantilever beam configuration to ascertain the mechanics of crack growth. Finite element (FE) simulations are deployed to determine the strain energy release rate (ERR) and to elucidate the salient features of the fracture process. It is shown that the channels induce a modulation of the ERR and enable a crack tip shielding mechanism. Besides, FE simulations based on a cohesive zone approach indicate the occurrence of crack pinning/depinning cycles that are validated via experiments. A highlight of the present study is the use of a mechanoluminescent (ML) coating to unravel the evolution of the transient stress field in the crack tip region. The coating comprises an optical epoxy resin loaded with doped strontium aluminate phosphors (SrAl2O4/Eu2+) and converts mechanical energy into light emission with intensity proportional to the magnitude of mechanical stress. By combining the ML emission patterns with the stress distribution obtained from FEA, we unveil interesting details of snap-through cracking in architected bio-inspired adhesive joints.

Effect of Strain Rates and Heat Exposure on Polyamide (PA12) Processed via Selective Laser Sintering.

The use of polymers in the transportation industry represents a great opportunity to meet the growing demand for lightweight structures and to reduce polluting emissions. In this context, additive manufacturing represents a very effective fabrication route for mechanical components with sophisticated geometry that cannot be pursued by conventional methods. However, understanding the mechanical properties of 3D-printed polymers plays a crucial role in the performance and durability of polymer-based products. Polyamide is a commonly used material in 3D printing because of its excellent mechanical properties. However, the layer-by-layer deposition process and ensuing auxiliary steps (e.g., post-processing heating) may affect the microstructure and mechanical properties of 3D-printed nylon with respect to the bulk counterpart. In this work, we explore the effect of displacement rate and heat exposure on the mechanical properties of 3D-printed polyamide (PA12) specimens obtained by selective laser sintering (SLS). Moreover, the thermal characteristics of the powders and sintered material were evaluated using differential scanning calorimetry (DSC). Our results highlight the expected rate dependency of mechanical properties and show that a post-processing heat treatment partly affects mechanical behavior.

Characteristics and Subjective Evaluation of an Intelligent Empowering Agent for Health Person Empowerment.

Empowerment is a process through which people acquire the necessary knowledge and self-awareness to understand their health conditions and treatment options, self-manage them, and make informed choices. Currently, few stand-alone applications for patient empowerment exist and people/patients often go on the Web to search for health information. Such information is mainly obtained through generic search engines and it is often overwhelming, too generic, and of poor quality. Intelligent Empowering Agents (IEA) can filter such information and assist the user in the understanding of health information about specific complaints or health in general. We have designed and developed a first prototype of an IEA that dialogues with the user in simple language, collects health information from the Web, and provides tailored, easily understood, and trusted information. It empowers users to create their own comprehensive and objective opinion on health matters that concern them. The paper describes the IEA main characteristics and presents the results of subjective tests carried out to assess the effectiveness of the IEA. Twenty-eight Master students in Digital Health filled an online survey presenting questions on usability, user experience and perceived value. Most respondents found the IEA easy to use and helpful. They also felt that it would improve communication with their doctors.

Islamic law and investments in children: Evidence from the Sharia introduction in Nigeria.

Islamic law lays down detailed rules regulating children's upbringing. This study examines the effect of such rules on investments in children by analysing the introduction of Sharia law in northern Nigeria. Triple-differences estimates using temporal, geographical and religious variation together with large, representative survey data show decreases in infant mortality. Official government statistics further confirm improvements in survival. Findings also show that Sharia increased vaccination rates, duration of breastfeeding and prenatal health care. Evidence suggests that Sharia improved survival by specifying strict child protection laws and by formalising children's duty to maintain their parents in old age or in sickness.

Finite Element Analysis of Crack Propagation in Adhesive Joints with Notched Adherends.

The adherends notching technique has been the subject of a few recent studies and consists of tailoring the geometry of the adjoined layers to mitigate the bondline peak stresses and enhance the joint strength. In the present study, we explored the effect of the adherends notching technique on crack propagation using finite element (FE) simulations based on the cohesive zone model (CZM) of fracture. Double cantilever beam (DCB) adhesive joints subjected to quasistatic loading were considered as a model material system. An array of equally spaced notches was placed on the faying sides of the adherends, oriented perpendicularly to the direction of crack growth. A parametric investigation was carried out to ascertain the role of the notches and the input cohesive properties on various performance metrics, e.g., load-displacement response and dissipated energy. The proposed notching strategy promotes an unstable crack pinning/depinning process, which effectively delays crack growth and increases the effective work of fracture. Additionally, we found that the overall behaviour is tunable by changing geometric (i.e., notch spacing and depth) and bondline material properties.

Effect of Mechanical Pretreatments on Damage Mechanisms and Fracture Toughness in CFRP/Epoxy Joints.

Adhesive bonding of carbon-fiber-reinforced polymers (CFRPs) is a key enabling technology for the assembly of lightweight structures. Surface pretreatment is necessary to remove contaminants related to material manufacturing and ensure bond reliability. The present experimental study focuses on the effect of mechanical abrasion on the damage mechanisms and fracture toughness of CFRP/epoxy joints. The analyzed CFRP plates were provided with a thin layer of surface epoxy matrix and featured enhanced sensitivity to surface preparation. Various degrees of morphological modification and fairly controllable carbon fiber exposure were obtained using sanding with emery paper and grit-blasting with glass particles. In the sanding process, different grit sizes of SiC paper were used, while the grit blasting treatment was carried by varying the sample-to-gun distance and the number of passes. Detailed surveys of surface topography and wettability were carried out using various methods, including scanning electron microscopy (SEM), contact profilometry, and wettability measurements. Mechanical tests were performed using double cantilever beam (DCB) adhesive joints. Two surface conditions were selected for the experiments: sanded interfaces mostly made of a polymer matrix and grit-blasted interfaces featuring a significant degree of exposed carbon fibers. Despite the different topographies, the selected surfaces displayed similar wettability. Besides, the adhesive joints with sanded interfaces had a smooth fracture response (steady-state crack growth). In contrast, the exposed fibers at grit-blasted interfaces enabled large-scale bridging and a significant R-curve behavior. While it is often predicated that quality composite joints require surfaces with a high percentage of the polymer matrix, our mechanical tests show that the exposure of carbon fibers can facilitate a remarkable toughening effect. These results open up for additional interesting prospects for future works concerning toughening of composite joints in automotive and aerospace applications.

Design, development and validation of a system for automatic help to medical text understanding.

OBJECTIVE: The paper presents a web-based application, SIMPLE, that facilitates medical text comprehension by identifying the health-related terms of a medical text and providing the corresponding consumer terms and explanations. BACKGROUND: The comprehension of a medical text is often a difficult task for laypeople because it requires semantic abilities that can differ from a person to another, depending on his/her health-literacy level. Some systems have been developed for facilitating the comprehension of medical texts through text simplification, either syntactical or lexical. The ones dealing with lexical simplification usually replace the original text and do not provide additional information. We have developed a system that provides the consumer terms alongside the original medical terms and also adds consumer explanations. Moreover, differently from other solutions, our system works with multiple languages. METHODS: We have developed the SIMPLE application that is able to automatically: 1) identify medical terms in a medical text by using medical vocabularies; 2) translate the medical terms into consumer terms through medical-consumer thesauri; 3) provide term explanations by using health-consumer dictionaries. SIMPLE can be used as a standalone web application or can it be embedded into common health platforms for real time identification and explanation of medical terms. At present, it works with English and Italian texts but it can be easily extended to other languages. We have run subjective tests with both medical experts and non-experts as well as objective tests to verify the effectiveness of SIMPLE and its simplicity of use. RESULTS: Non-experts found SIMPLE easy to use and responsive. The big majority of respondents confirmed they were helped by SIMPLE in understanding medical texts and declared their willingness to continue using SIMPLE and to recommend it to other people. The subjective tests, conducted with medical experts on a set of Italian radiology reports, showed an agreement between SIMPLE and the experts, on the highlighted medical terms, that ranges between 74.05 % and 81.16 % as well as an agreement of around 60 % on the consumer term translation. The objective tests showed that the consumer terms, provided by SIMPLE, are, on average, eighteen times more familiar than the relative medical terms so proving, once more, the effectiveness of SIMPLE in simplifying the medical terms. CONCLUSIONS: The performed tests demonstrate the effectiveness of SIMPLE, its simplicity of use and the willingness of people in continuing with its use. SIMPLE provides, with a good agreement level, the same information that medical experts would provide. Finally, the consumer terms are 'objectively' more familiar than the related technical terms and as a consequence, much easier to understand.

Toughness amplification in copper/epoxy joints through pulsed laser micro-machined interface heterogeneities.

This work addresses the mechanics of debonding along copper/epoxy joints featuring patterned interfaces. Engineered surface heterogeneities with enhanced adhesion properties are generated through pulsed laser irradiation. Peel tests are carried out to ascertain the effect of patterns shape and area fraction on the mechanical response. Experimental results are evaluated with the support of three-dimensional finite element simulations based on the use of cohesive surfaces. Results discussion is largely framed in terms of effective peel force and energy absorbed to sever the samples. It is shown that surface heterogeneities act as sites of potential crack pinning able to trigger crack initiation, propagation and arrest. Surface patterns ultimately enable a remarkable increase in the effective peel force and dissipated energy with respect to baseline homogeneous sanded interface.

Three-point bending tests of zirconia core/veneer ceramics for dental restorations.

Introduction. The mechanical strength and the surface hardness of commercially available yttrium-doped zirconia were investigated. Furthermore, a comparative study of eight different ceramic veneers, to be used for the production of two-layered all-ceramic restorative systems, was carried out. Materials and Methods. Four types of zirconia specimens were analyzed, according to a standard ISO procedure (ISO 6872). Besides, two-layered zirconia-veneer specimens were prepared for three-point bending tests. Results. A strong effect of the surface roughness on the mechanical strength of zirconia specimens was observed. Finally, a comparative study of eight commercially available veneering ceramics shows different modes of failure between the selected veneers. Conclusion. The results indicate that close attention should be paid to the preparation of zirconia-based crowns and bridges by CAD/CAM process, because surface roughness has an important effect on the mechanical strength of the material. Finally, the results of the mechanical tests on two-layered specimens represent an important support to the choice of the veneering ceramic.

Access to non-pecuniary benefits: does gender matter? Evidence from six low- and middle-income countries.

BACKGROUND: Gender issues remain a neglected area in most approaches to health workforce policy, planning and research. There is an accumulating body of evidence on gender differences in health workers' employment patterns and pay, but inequalities in access to non-pecuniary benefits between men and women have received little attention. This study investigates empirically whether gender differences can be observed in health workers' access to non-pecuniary benefits across six low- and middle-income countries. METHODS: The analysis draws on cross-nationally comparable data from health facility surveys conducted in Chad, Côte d'Ivoire, Jamaica, Mozambique, Sri Lanka and Zimbabwe. Probit regression models are used to investigate whether female and male physicians, nurses and midwives enjoy the same access to housing allowance, paid vacations, in-service training and other benefits, controlling for other individual and facility-level characteristics. RESULTS: While the analysis did not uncover any consistent pattern of gender imbalance in access to non-monetary benefits, some important differences were revealed. Notably, female nursing and midwifery personnel (the majority of the sample) are found significantly less likely than their male counterparts to have accessed in-service training, identified not only as an incentive to attract and retain workers but also essential for strengthening workforce quality. CONCLUSION: This study sought to mainstream gender considerations by exploring and documenting sex differences in selected employment indicators across health labour markets. Strengthening the global evidence base about the extent to which gender is independently associated with health workforce performance requires improved generation and dissemination of sex-disaggregated data and research with particular attention to gender dimensions.

Physician shortages in rural Vietnam: using a labor market approach to inform policy.

This paper investigates labor market dynamics for physicians in Vietnam, paying particular attention to geographic distribution and dual job holding. The analysis is based on a survey of a random sample of physicians in 3 regions in 2009-10. We found that the labor market for physicians in Vietnam is characterized by very little movement among both facility levels and geographic areas. Dual practice is also prominent, with over one-third of physicians holding a second job. After taking account of the various sources of income for physicians and controlling for key factors, there is a significant wage premium associated with locating in an urban area. This premium is driven by much higher earnings from dual job holding rather than official earnings in the primary job. There are important policy implications that emerge. With such low job turnover rates, policies to increase the number of physicians in rural areas could focus on initial recruitment. Once in place, physicians tend to remain in their jobs for a very long time. Lastly, findings from an innovative discrete choice experiment suggest that providing long-term education and improving equipment are the most effective instruments to recruit physicians to work in rural areas.

A review of patented works on the mechanical characterization of materials at micro- and nano-scale.

In recent years, the development of cost-effective processing techniques, novel design concepts and new materials paved the way to a widespread diffusion of micro- and nano-electro-mechanical systems (NEMS/MEMS). Obviously, the reliability as well as the performance of NEMS/MEMS depend on the corresponding materials properties, which in turn should be determined using ad-hoc small samples fabricated at the relevant size-scale. For this reason, in the last decade research efforts have been devoted to the development of experimental techniques suitable for the mechanical characterization of materials at micro- and nano-scale. There are many contributions stemming from this research area, the purpose of the present work is to give an overview of the most recent patented works. The focus will be directed to selected patents on the mechanical characterization of both micro- and nanosamples, like nanotubes and nanowires. Special emphasis will be given to the methods suited for the determination of elastic properties, fracture resistance and residual stresses of materials.