First-generation intervertebral disc prostheses (IDPs) have well-established design fea-tures, but an inconsistent functional performance and they are not entirely accepted for clinical use. Currently, second-generation IDPs aim to overcome first-generation problems. Design features and performance of IDPs are related from first- to second-generation, but the relationship is unclear. In 1990, Hedman et al. determined design criteria for the first generation, but the lit-erature has not reported any further criteria for the second generation. This paper is focused on design criteria for second-generation prostheses, clarifying the relationship between the design features and performance of IDPs. We analyzed biomechanical prop-erties of natural intervertebral discs and technological evolution of IDPs to characterize functional performance. A group of functional parameters were identified. A comprehensive review of the literature regarding design criteria showed inconsistent and ambiguous criteria. So, a structure of criteria based on information content is proposed to avoid these conflicts. The criteria are structured into three parts including the functional parameters. In a straight relation to functionality, three design criteria are sufficient to evaluate holistically the features of the second-generation IDPs. The criteria avoid the absence or incongruence of information of the design features and relate the performance of IDP to its features in the route to overcome functional problems.

A novel method capable of generating printed circuits using concentrated solar energy (CSE) is proposed. The open literature has reported that no method employs CSE to obtain printed circuits additively. Based on the Mill & Fill method, a conductive material (Sn63Pb37) is deposited inside a trench milled on a thermoplastic substrate (PETG). The concentrated solar beam melts the conductive material to form a solid trace, while the substrate relaxes its structure and allows the inclusion of the path. The resulting hybrid joining between plastic and metal is like those obtained by LAMP (laser-assisted joining of metal-polymer). The 20 conducted tests found that the magnitude of direct solar radiation and the overall system efficiency are the most influential variables on the exposure time of the trace to the solar spot. Each test, with its conditions, was simulated in COMSOL Multiphysics software, and the temperatures obtained experimentally were compared with those obtained by simulation. This proposal is expected to serve as a bridge between both fields of study so that solar concentrators will be considered in the additive manufacturing of printed circuits and expand CSE's potential for developing consumer goods.

Objetivo: Mejorar la comprensión de los cambios generados por los procedimientos restaurativos a través de modelos fotoelásticos. La reconstrucción dental debe fundamentarse en principios de oclusión para no provocar puntos prematuros de contacto durante los procedimientso de preparación y restauración que pueden provocar transtornos como el trauma oclusal, disfuncion de la ATM, o fracturas. En este documento se presenta un metodo didactico para visualizar de forma objetiva las cargas oclusales y su distribución. Materiales y métodos: Se realizaron modelos fotoelasticos de dientes y segmentos maxilares, para visualizar los efectos de las preparaciones dentales y restauraciones, asi como el desgaste de puntos prematuros de contacto. Resultados: Por fotoelasticidad se analizó la dirección, intensidad y distribución de esfuerzos en la corona y soporte óseo. Conclusiones: La tecnica permite visualizar cómo se afectan las estructuras desde la preparación cavitaria, los diferentes esfuerzos con fresas de diamante o carburo, además de observar cómo un punto prematuro de contacto no solo afecta al órgano que lo contiene sino a estructuras aledañas.

Objective:To improve the understanding of the changes generated by restorative procedures through photoelastic models. Dental reconstruction should be based on principles of occlusion in order not to cause premature contact points during preparation and restoration procedures that can lead to disorders such as occlusal trauma, temporo-mandibullary joint dysfunction, or fractures. This paper presents a didactic method to objectively visualize occlusal loads and their distribution. Materials and methods:Photoelastic models of teeth and maxillary segments were made to visualize the effects of dental preparations and restorations, as well as the wear of premature contact points. Results:The direction, intensity and distribution of stresses in the crown and bone support were analyzed by photoelasticity. Conclusions:The technique allows visualization of how the structures are affected from the cavity preparation, the different stresses with diamond or carbide burs, in addition to observing how a premature contact point not only affects the organ that contains it but also the surrounding structures.

The number of existing tools, principles and approaches to assess sustainability in products is growing to meet industry and society needs. For those related to design and development in universities, research institutes and companies it is a fundamental issue to recognize features and details of the sustainability assessment tools in order to select the one that best fits their particular needs. This paper describes the outcomes of a product sustainability assessment carried out at Universidad Nacional Autónoma de México, UNAM. The approach followed by the authors in this assessment was aimed at comparing the results provided by a set of software tools and a previous sustainability integrated-criteria tool developed by the research group. The main contribution of this paper is the insight on the software tools used and on the results of the assessment since the design point of view. The results of the assessment included metrics such as: carbon footprint, energy use, end of life potential, toxicity, eco-toxicity, human toxicity, recyclability, and others. In the first part of the paper, an introduction of the criteria and the software based tools for sustainability assessment used by the authors is presented. Then a justification of the tools used and an explanation on how the comparison was achieved are given. The product used as a case study and the results of its sustainability assessment are presented. The case study part is a home appliance subsystem. In the end of the paper conclusions, insights and further work are given.

This paper presents the literature review on the design criteria for intervertebral disc prosthesis. The design criteria relate to the design features that intervertebral prosthesis must accomplish (i.e. fixation to bones, spine mobility, energy absorption and etcetera). The need to improve the performance has led to changes in the features which reflect in the current design criteria.Currently, the disc prosthesis technology is experiencing a generational change. The first generation was thoroughly studied while the second generation is in the clinical tests stage. During the time the first generation prostheses were applied in patients there was not a clear trend in the clinical results which produced a lack of trust and reliability in the performance of the disc prosthesis. The changes in the design features of one generation compared to the next generation are based in the deepening in the knowledge of the problem and the results obtained with the first generation prostheses.Some design criteria were identified for the first generation. These criteria were not completely characterized since there was not enough information to be used by the designer. This lack of characterization of most design criteria produced many different versions without a clear focus which help to define the basic design features of disc prostheses. This document presents the necessary information to thoroughly characterize the design criteria outlining the missing information for the design criteria found. An analysis is done of the design criteria in the second generation of prosthesis.Finally if the information contained in the design criteria is enough, the clinical results would be better focused to achieve a more repeatable, reproducible and reliable process for a total disc intervertebral prosthesis replacement as now is considered the vertebral fusion, this is a gold standard.

An innovative product may not be successful when launched to the market arena; this paper explores the use of TRIZ tools at early stages of the user centered design approach (UCD) to develop new products. This paper proposes an application of TRIZ tools through an abstract analysis of the customer's interactions and the context; this allows a deeper understanding and a comprehensive definition of customer requirements. The authors' proposal is aimed at identifying innovative commercial successful opportunities. The main contribution of this paper is centered on the integration of the value creation and innovation tools of the UCD approach and TRIZ at early design stages. The first part of the paper describes the link between relevant design methodologies and innovation tools applied by UCD and TRIZ. The next section discusses the integration of UCD and TRIZ. The third section presents applications of this integration. Finally conclusions are presented and further work is described

This paper proposes a methodology that integrates the user centered design (UCD) approach and the TRIZ theory. This methodology is divided in four stages: observation, framework, imperatives and solutions. The integration feasibility of the methodologies mentioned above is showed with a case study. This proposal is aimed at identifying innovation opportunities, and somehow it addresses to save time during the product design. The proposed methodology is applied in a case study, which is the design of a geriatric wheelchair. The design of the wheelchair includes the activities carried out from user needs gathering to the functional prototyping of a design concept.