Materials and processes for 3D printed electronics

Dissertação de mestrado integrado em Engenharia de MateriaisThe traditional manufacturing of electronic components consists of complex and with high environmental impact methods. Those materials are potentially dangerous for both environmental and public health, during the manufacturing process and at the end of the product lifetime when not correctly handled. Thus, the goal consists of producing in a simpler/cheaper way and with lower environmental impact, materials to be used into electronic components. In this work inks based of a natural polymer (carrageenan) and ultrapure water (a “green” solvent) were used to produce more environmentally friendly printable electronic components. To achieve magnetic, conductive and dielectric properties CoFe2O4 (CFO), multiwalled carbon nanotubes (MWCNTs) and BaTiO3 (BTO) nanoparticles were added, respectively. To promote a better dispersion and, therefore, to improve the properties of the final product, Triton X-100 was used as a surfactant. Trition X-100 was selected among other surfactants, since it has shown better results on initial selection tests. For the printing process, the most suitable parameters were selected according to the ink viscosity to improve the process as well as to optimize the method to introduce the ink into the syringe. Morphological, thermal, and mechanical tests were performed in order to evaluate the effects of fillers addition and concentration. Dielectric tests were carried out to the samples with BTO. The higher dielectric constant has been obtained for the sample with 20 wt.% BTO content, reaching 1.3 x 104 at 10 kHz. The electrical conductivity evaluation in the samples with MWCNTs shows that a DC conductivity of 0.026 S.m-1 is achieved for the sample with 5 wt.% MWCTNs content. Vibrating sample magnetometer (VSM) test was performed to analyse the magnetic behaviour of the composite samples with CFO, a saturation magnetization of 11 emu.g-1 being obtained for the samples with 20 wt.% CFO content. The inks developed on this work highlights the relevance of the implementation of natural materials as a base for the development of functional and multifunctional materials. Adding to that, this work can also act as an incentive to the study of materials and manufacturing procedures with lower environmental risks with the capacity of still answering society’s needs.A manufatura tradicional de componentes eletrónicos consiste em métodos complexos, com elevado impacto ambiental, quer por gasto energético quer pelos materiais usados que são potencialmente nocivos para o ambiente e para a saúde pública, durante o processo de fabrico e no final de vida do produto, quando não corretamente processados. Visto isto, o objetivo deste projeto consiste em produzir de um modo simples, com baixo custo e com menor impacto ambiental materiais que possam ser usados em componentes eletrónicos. Assim, neste trabalho foram desenvolvidas tintas à base de um polímero natural (carragenina) e água ultrapura (usada como solvente “verde”) para produzir componentes eletrónicos impressos mais amigos do ambiente. De modo a fornecer propriedades magnéticas, condutivas e dielétricas foram adicionadas nanopartículas de CoFe2O4 (CFO), Multicamadas de Nanotubos de Carbono (MWCNTs) e BaTiO3 (BTO), respetivamente. Para promover uma melhor dispersão foi usado Triton X-100 como surfactante. No processo de impressão foram estudados os parâmetros mais adequados de acordo com a viscosidade da tinta para tornar o processo mais rentável assim como tentar encontrar o melhor método para introduzir a tinta dentro da seringa com a menor formação de bolhas possível. Os testes morfológicos, térmicos e mecânicos foram feitos para todas as amostras para comparar as propriedades fornecidas pela adição das partículas, avaliando a sua interferência com o aumento da concentração de filler. Os testes dielétricos foram realizados para as amostras de BTO. A constante dielétrica com valor mais elevado foi obtido para a amostra com concentração de 20 wt.% BTO, atingindo 1.3 x 104 a 10 kHz. A avaliação dos testes de condutividade elétrica nas amostras de MWCNTs, mostraram uma condutividade DC de 0.026 S.m-1 foi obtida para a mostra com concentração de 5 wt.% MWCTNs. O teste de mapeamento de fluxo de valor (VSM) foi realizado para analisar o comportamento magnético do compósito com partículas de CFO, a magnetização de saturação de 11 emu.g-1 foi obtida para a amostra com concentração de 20 wt.% CFO . As tintas desenvolvidas neste trabalho veem dar relevância à implementação de materiais naturais como base para o desenvolvimento de materiais funcionais e multifuncionais. Vem também promover o estudo de materiais e métodos de produção com menos impacto ambiental e que consigam manter a resposta às necessidades da sociedade

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research