ADS Group

Part of the June 2026 issue supplement, to be published in its entirety on May 12, 2026.

A alumina é um dos principais materiais cerâmicos e apresenta várias características muito interessantes, como elevado ponto de fusão (2.072 °C), baixa densidade (3,95 g/cm3), elevada transparência e baixo índice de refração (n = 1,7282). Devido a essas características é utilizada para fabricação de refratários, materiais de polimento, lâmpadas de sódio, dentre outras aplicações. O uso de aditivos que tendem a segregar nas interfaces de materiais nanométricos tem sido utilizado como uma estratégia para melhorar diversas propriedades dos nanomateriais. O Li2O tem sido utilizado como aditivo na estrutura do aluminato de magnésio para diminuir a temperatura de sinterização. Porém, pouco se sabe dos efeitos da dopagem do Li2O na estrutura da alumina. Assim, este projeto propôs um estudo detalhado dos efeitos da dopagem do Li2O na alumina nanométrica. Para isso, pós nanométricos foram preparados pelo método dos precursores poliméricos. As resinas resultantes foram dopadas com diferentes quantidades de LiCl (0,1, 0,5, 1, 3, 5 e 10 em mol%), seguida por uma calcinação a 650 e 750 ºC por 15h. Os pós foram caracterizados por difração de raios X (DRX), fluorescência de raios X (FRX), adsorção de N2 (BET) e densidade por picnometria de hélio. A segregação do lítio, isto é, o excesso na superfície e nos contornos de grão foram determinados pelo método de lixiviação seletiva. Os resultados de DRX mostraram que os pós apresentaram majoritariamente a fase gama após calcinação, porém em uma composição houve formação de uma segunda fase, o aluminato de lítio (LiAl5O8). Os tamanhos de cristalitos do material variaram entre 3,3 e 9,2 nm, enquanto as áreas de superfície específica ficaram entre 82,0 e 119,9 m²/g. Verificou-se uma tendência de diminuição de contornos de grão quando o percentual de lítio foi aumentado. As análises químicas indicaram que o lítio se acomoda bem na estrutura da -alumina até 650 ºC, porém a 750 ºC se volatiliza. O método de lixiviação seletiva se mostrou eficaz na quantificação do excesso de superfície e mostrou que o lítio segrega de fato nas interfaces da alumina.

ABSTRACTCircular hollow sections (CHS) represent several advantages, such as uniform behaviour in all directions, possibility to obtain composite behaviour by concrete infill, hence high strength, stability and good fire resistance. Moreover, their aesthetic appeal has a great potential for the decision maker's attention, be that the architect or the building owner. However, they are not widely adopted in practice due to the complexity and high cost of their joint details. EU‐RFCS project LASTEICON (Laser Technology for Innovative Connections in Steel Construction), started on July 2016 [1] proposes simpler joint solutions with reduced fabrication costs, to be adopted between CHS columns and I beams, making use of laser cutting technology (LCT). The primary objective of the LASTEICON project is to overcome the complexity of steel joints between CHS columns and I beams, and let engineers and architects exploit the outstanding structural properties of hollow section profiles. Laser cutting will allow the reduction of the shop fabrication time, obtaining higher precision high quality joint fabrication, and improving workplace safety reducing the amount of manual labor while increasing computer‐programmed automation. This paper presents the preliminary results obtained in the Work‐Package 1 of the LASTEICON project (www.lasteicon.eu), which consisted in a study of tolerance optimization for an efficient fabrication of I‐beam‐to‐CHS column joints.

New approaches in the use of media and technology provide the opportunity to give children's voices a space to express their unique interests. These new forms of video and audio use create a new type of engagement for children to communicate in ways that makes it relevant to their identity. We are looking to tap into the already prevalent use of these technologies by children to establish a conversation about issues that are important to them. Giving children the opportunity to create and exercise control over the content of their creation can foster children centered programs and establish a conversation with larger communities in a local, national and global stage. Exploring the potential of audio and video in innovative ways will be the focus of this workshop. Workshop participants will present specific case studies and projects and discuss informal trends identified through their work on children's new uses of media. This workshop will provide insight in how technology is being used and ways that it can provide a new communication platform for children.

There are situations where it is advantageous to visually obscure through glass, to an external observer, the movement of people within a well lit room. It may be that the building use has changed or existing measures which had provided obscuration such as 'Bomb-blast' curtains have been discontinued. Recognising that implemented solutions must create the minimum disruption to outward visibility and involve the least procedural effort (be simple to use), the Centre for Protection of National Infrastructure, CPNI, commissioned this study, defining key requirements including: (a) Automatic or simple manual operation (b) Obscuration of movement within the building from outside (c) Varying levels of obscuration depending on the difference in internal and external light levels. (d) Minimum disruption to outward visibility (e) Acceptable for use on heritage and iconic sites (f) Easy to retrofit (g) Low cost This report reviews earlier work carried out into the protection of Guardrooms by the use of lighting techniques coupled with the use of reflective and screen printed films. Other innovative solutions including Electrochromatic controllable glazing which may prove more appropriate to office and commercial buildings are also considered. It is seen that some measures, (window films or blinds), are cost effective and unsophisticated while more complex automatic systems using reactive glazing can offer critical design advantages. It must be noted however that some of the key requirements are mutually exclusive and any solution chosen will always be a compromise based on client needs and circumstances.