Spark Assisted Chemical Engraving: A Novel Approach for Quantifying the Machining Zone Parameters Using Drilling Forces

Glass has stirred human interest since the dawn of history due to its unique properties including its high mechanical strength, transparency, thermal and chemical properties. With the great technological advancement that we are witnessing today in the micro-technology field, glass micro-machining has already found applications in the optical, electronics, and biomedical applications. In fact, such applications require high-aspect-ratio structures of defined wall flatness and surface roughness. There exist nowadays several glass micro-machining technologies that are being developed to meet this demand. These are based on thermal (laser), chemical (dry and wet etching), and mechanical (ultrasonic, abrasive and diamond-tool drilling) processes. Spark Assisted Chemical Engraving (SACE) is a non conventional glass micro-machining technology which is based on discharge generation at the tool tip. This is known to heat up the glass surface. Today, the machining mechanism is highly questionable where it is explained differently by many researchers in the field. This is due to the fact that the basic understanding about the process and the local variables in the machining zone is still missing. Although research about SACE drilling has allowed achieving deeper and smaller holes, these results remain specific to certain machining conditions. In fact, they are achieved experimentally by trial and error due to limited knowledge about the process fundamentals. Therefore, it can be said that SACE machining is still blind where the idea of doing feed-back drilling has not been explored sufficiently. These are the basic reasons of why SACE glass machining remains in laboratories and is never applied in industry. The aim of this work is to unveil basic information about the SACE machining process and the local parameters in the machining zone. For this purpose, a methodology is developed for measuring the local machining zone parameters based on the force exerted on the tool during machining. Measurement errors caused by tool bending, wear and thermal expansion are quantified and considered while measuring and analysing the machining forces. Thus, in a first step, the machining force is characterized and analysed to get a deeper understanding about its origin and the reasons of its formation. This signal is used in a second step to extract information about local variables including the machining gap size, the local glass surface temperature and the origin of its texture. Based on the understanding of the machining process that this work brings, a thermal model is built which describes heat transfer to the glass surface. The agreement between calculations and measurements ensures the validity of both the model and measurement methodology. Based on the results, the machining mechanism is explained as a thermal assisted etching process. Machining can exist in two modes based on the electrolyte state (aqueous or molten) which depends on the local flushing. Force signal readings showed that tool-glass bonding can occur during machining which may hinder the drilling progress. Based on the understanding that this work brought about the machining mechanism and the factors that influence it, force feedback algorithms are built with the aim to establish a balance between local heating and flushing. The efficiency of the various algorithms in enhancing the drilling performance was compared and assessed based on the resulting drilling time. The knowledge acquired allowed building algorithms that succeeded in drilling high-aspect-ratio holes up to 1:9 while using very small tools (70 microns diameter) without breakage. The resulting drilling time is dramatically reduced to few seconds compared to several minutes in the state-of-the-art SACE drilling

Do digital innovations for HIV and sexually transmitted infections work? Results from a systematic review (1996-2017).

OBJECTIVE: Digital innovations with internet/mobile phones offer a potential cost-saving solution for overburdened health systems with high service delivery costs to improve efficiency of HIV/STI (sexually transmitted infections) control initiatives. However, their overall evidence has not yet been appraised. We evaluated the feasibility and impact of all digital innovations for all HIV/STIs. DESIGN: Systematic review. SETTING/PARTICIPANTS: All settings/all participants. INTERVENTION: We classified digital innovations into (1) mobile health-based (mHealth: SMS (short message service)/phone calls), (2) internet-based mobile and/or electronic health (mHealth/eHealth: social media, avatar-guided computer programs, websites, mobile applications, streamed soap opera videos) and (3) combined innovations (included both SMS/phone calls and internet-based mHealth/eHealth). PRIMARY AND SECONDARY OUTCOME MEASURES: Feasibility, acceptability, impact. METHODS: We searched databases MEDLINE via PubMed, Embase, Cochrane CENTRAL and Web of Science, abstracted data, explored heterogeneity, performed a random effects subgroup analysis. RESULTS: We reviewed 99 studies, 63 (64%) were from America/Europe, 36 (36%) from Africa/Asia; 79% (79/99) were clinical trials; 84% (83/99) evaluated impact. Of innovations, mHealth based: 70% (69/99); internet based: 21% (21/99); combined: 9% (9/99).All digital innovations were highly accepted (26/31; 84%), and feasible (20/31; 65%). Regarding impacted measures, mHealth-based innovations (SMS) significantly improved antiretroviral therapy (ART) adherence (pooled OR=2.15(95%CI: 1.18 to 3.91)) and clinic attendance rates (pooled OR=1.76(95%CI: 1.28, 2.42)); internet-based innovations improved clinic attendance (6/6), ART adherence (4/4), self-care (1/1), while reducing risk (5/5); combined innovations increased clinic attendance, ART adherence, partner notifications and self-care. Confounding (68%) and selection bias (66%) were observed in observational studies and attrition bias in 31% of clinical trials. CONCLUSION: Digital innovations were acceptable, feasible and generated impact. A trend towards the use of internet-based and combined (internet and mobile) innovations was noted. Large scale-up studies of high quality, with new integrated impact metrics, and cost-effectiveness are needed. Findings will appeal to all stakeholders in the HIV/STI global initiatives space

Impact of a personalised, digital, HIV self-testing app-based program on linkages and new infections in the township populations of South Africa.

INTRODUCTION: Implementation data for digital unsupervised HIV self-testing (HIVST) are sparse. We evaluated the impact of an app-based, personalised, oral HIVST program offered by healthcare workers in Western Cape, South Africa. METHODS: In a quasirandomised study (n=3095), we recruited consenting adults with undiagnosed HIV infection from township clinics. To the HIVST arm participants (n=1535), we offered a choice of an offsite (home, office or kiosk based), unsupervised digital HIVST program (n=962), or an onsite, clinic-based, supervised digital HIVST program (n=573) with 24/7 linkages services.With propensity score analyses, we compared outcomes (ie, linkages, new HIV infections and test referrals) with conventional HIV testing (ConvHT) arm participants (n=1560), recruited randomly from geographically separated clinics. RESULTS: In both arms, participants were young (HIVST vs ConvHT) (mean age: 28.2 years vs 29.2 years), female (65.0% vs 76.0%) and had monthly income <3000 rand (80.8% vs 75%).Participants chose unsupervised HIVST (62.7%) versus supervised HIVST and reported multiple sex partners (10.88% vs 8.7%), exposure to sex workers (1.4% vs 0.2%) and fewer comorbidities (0.9% vs 1.9%). Almost all HIVST participants were linked (unsupervised HIVST (99.7%), supervised HIVST (99.8%) vs ConvHT (98.5%)) (adj RR 1.012; 95% CI 1.005 to 1.018) with new HIV infections: overall HIVST (9%); supervised HIVST (10.9%) and unsupervised HIVST (7.6%) versus ConvHT (6.79%) (adj RR 1.305; 95% CI 1.023 to 1.665); test referrals: 16.7% HIVST versus 3.1% ConvHT (adj RR 5.435; 95% CI 4.024 to 7.340). CONCLUSIONS: Our flexible, personalised, app-based HIVST program, offered by healthcare workers, successfully linked almost all HIV self-testers, detected new infections and increased referrals to self-test. Data are relevant for digital HIVST initiatives worldwide

Recycling of dredged sediments and excavated soil in the formulation of printable construction materials

L’impression 3D du béton est l'une des technologies de construction les plus récentes. Elle offre des avantages et des opportunités par rapport à la méthode de construction traditionnelle, notamment la rapidité de la construction et la flexibilité de la conception architecturale. Cependant, la plupart des encres imprimables utilisées à ce jour nécessitent une forte teneur en ciment, dont la production génère de fortes émissions de CO2. La réduction de l'impact environnemental du béton imprimable est actuellement au centre des préoccupations des chercheurs qui visent à utiliser des matériaux alternatifs pour remplacer le ciment et réduire sa forte consommation dans les mélanges imprimables en 3D. Ces travaux de recherche portent sur la valorisation de matériaux alternatifs et innovants, actuellement considérés comme des déchets, dans l'impression 3D, afin de développer des mélanges imprimables à faible impact environnemental. Les matériaux alternatifs utilisés sont les sédiments de dragage, les poudres de fibres de verre polyester et la terre excavée. Ces matériaux sont choisis pour leur potentiel de valorisation, leurs propriétés intrinsèques et pour la nécessité urgente de les gérer en raison de leur grande quantité. Par ailleurs, peu de travaux sont consacrés à la valorisation de ces types de matériaux dans l'impression 3D du béton, d’où l’objectif de cette thèse. Une méthodologie expérimentale est ainsi mise en œuvre pour développer des mélanges optimaux. Tout d'abord, l'extrudabilité et la buildabilité sont évaluées et vérifiées afin de valider l’imprimabilité des mélanges développés. Ensuite, les propriétés à l’état frais et durci des mortiers imprimables sont étudiées. De plus, dans ces travaux, différentes échelles d'impression sont testées, depuis l'échelle du laboratoire jusqu’à celle d'une imprimante 3D. Dans la première partie de l’étude, le sédiment flash calciné est utilisé dans une formulation témoin imprimable, produisant un liant binaire (ciment/sédiment flash calciné) et un liant ternaire (ciment/sédiment flash calciné/filler calcaire), et les poudres de fibres de verre polyester sont utilisées, en tant que renfort, dans la formulation témoin, substituant une partie du sable. Dans la deuxième partie de l’étude, la terre est utilisée en tant que substitut total du sable. Les résultats de la première partie de l’étude montrent que plusieurs mélanges contenant du sédiment flash calciné sont imprimables. Ces mélanges contiennent 5 et 10% de sédiment lorsque le sédiment est valorisé seul, et 10 et 20% de sédiment lorsqu'il est valorisé avec 20 et 30% de filler calcaire, respectivement. Une substitution du ciment de 50% est donc atteinte avec le mélange imprimable contenant 20% de sédiment et 30% de filler calcaire. En outre, les mélanges contenant jusqu'à 10% de poudres de fibres de verre polyester sont également imprimables. D’autre part, les résultats de la deuxième partie de l’étude montrent que les formulations développées avec un taux élevé de terre excavée et une faible teneur en ciment sont imprimables et résistantes. Les formulations imprimables contiennent différentes quantités de terre, environ 2, 4 et 6 fois la quantité du ciment, la formulation la plus écologique ayant une teneur en terre de 1602 kg/m3 et une teneur en ciment de 282 kg/m3. Ces travaux de recherche mettent en évidence la possibilité de développer de nouveaux mélanges écologiques et résistants à base de matériaux de substitution, qui peuvent être utilisés dans des applications de construction par impression 3D.Concrete 3D Printing is one of the newest technologies in the field of construction. It offers advantages and opportunities over the traditional construction method, notably speed of construction and flexibility of architectural design. However, most printable materials used nowadays require a high cement content, the production of which generates significant CO2 emissions. Reducing the environmental impact of printable concrete is currently the focus of researchers who aim to use alternative materials to replace cement and reduce its high consumption in 3D printable mixes. This research work focuses on the valorization of alternative and innovative materials, currently considered as waste, in 3D printing, to develop printable mixtures with low environmental impact. The alternative materials used are dredged sediments, polyester glass-fiber powders and excavated soil. These materials are chosen for their recycling potential, their intrinsic properties, and the urgency of their management due to their large quantity. Moreover, little work is devoted to the recycling of these specific types of waste in concrete 3D printing, hence the objective of this thesis. An experimental methodology is therefore implemented to develop optimal mixtures. First, the extrudability and buildability are evaluated and verified in order to validate the printability of the developed mixes. Then, the fresh and hardened properties of the printable mortars are studied. Furthermore, in this research, different printing scales are tested, from the laboratory scale to the 3D printer scale. In the first part of the study, flash-calcined sediment is used in a printable control mixture, producing a binary binder (cement/flash-calcined sediment) and a ternary binder (cement/flash-calcined sediment/limestone filler), and polyester glass-fiber powders are used, as reinforcement, in the control mixture, substituting a portion of the sand. In the second part of the study, excavated soil is used as a total substitute for sand. The results of the first part of the study show that several mixtures containing flash-calcined sediment are printable. These mixtures contain 5 and 10% of sediment when used alone, and 10 and 20% of sediment when used with 20 and 30% of limestone filler, respectively. A cement substitution of 50% is therefore achieved with the printable mixture containing 20% of sediment and 30% of limestone filler. In addition, mixtures containing up to 10% of polyester glass-fiber powders are also printable. Furthermore, the results of the second part of the study show that formulations with a high content of excavated soil and a low cement content are printable and resistant. The printable formulations contain different amounts of soil, about 2, 4 and 6 times the amount of cement, with the most environmentally friendly formulation having a soil content of 1602 kg/m3 and a cement content of 282 kg/m3. This research work highlights the possibility of developing new ecological and resistant mixtures based on alternative materials that can be used in 3D printing construction applications

Prevalence of Dietary Supplement Use among Athletes Worldwide: A Scoping Review

Athletes represent a major part of dietary supplement users. This scoping review aims to explore the prevalence of dietary supplement use among athletes worldwide, most commonly used supplements, sources of information on dietary supplements and their reasons for use of these supplements. PubMed, CINAHL, MEDLINE, and PsycInfo were searched for original research articles. Studies were included if they involved athletes, identified the prevalence of dietary supplement use, and were published after 2017. A total of 26 articles were reviewed. Prevalence of dietary supplement use varied among articles, but sex-based differences related to the types of used dietary supplements existed. Generally, the findings were consistent in terms of reasons for use and sources of information. Unfortunately, the lack of homogeneity regarding the definition of dietary supplements, definition of use, reporting timeframes, and data collection methods complicates the attempt to compare the findings among studies

Education Interventions to Improve Knowledge, Beliefs, Intentions and Practices with Respect to Dietary Supplements and Doping Substances: A Narrative Review

The misuse of dietary supplements and doping substances is commonly associated with toxicity, nutritional imbalances, and health and psychological consequences. This is alarming especially in light of the increasing prevalence of the use of dietary supplements and doping, particularly among young adults including athletes. There is evidence that education interventions can lead to improved knowledge, intentions, and practices. However, no review has summarized and evaluated the effectiveness of such interventions. The aim of this article is to review the characteristics, contents and effects of education interventions that were designed and implemented to improve knowledge, attitudes, beliefs and intentions with respect to the use of dietary supplements and doping agents in different populations. PubMed, Scopus, CINAHL, PsycInfo and Google Scholar were searched for English-language education interventions targeting dietary supplements and doping substances. A total of 20 articles were identified and have generally provided consistent findings. Most interventions reported a significant improvement in knowledge on dietary supplements and doping agents. Unfortunately, the heavy reliance on self-reported assessment tools limits the validity of these interventions, with almost all articles targeting athletes and adolescents

Dietary Supplements: A Gateway to Doping?

Dietary supplements are widely used among athletes, but many may be unaware of the potential for unintentional doping, especially considering that supplements can often be contaminated with prohibited substances. The reason behind the widespread use of dietary supplements among athletes is often cited as being for the purposes of enhancing health or performance. However, many athletes turn to unreliable sources of information, and often lack knowledge of dietary supplement regulations. The aim of this narrative review is to explore the current research surrounding the psychological constructs (such as norms, attitudes, and beliefs) related to dietary supplement use among athletes that may lead to inadvertent doping. This review also covers possible programme structures that may be effective at preventing inadvertent doping

Recycling of Flash-Calcined Dredged Sediment for Concrete 3D Printing

Due to the large volumes of sediments dredged each year and their classification as waste materials, proper management is needed to efficiently dispose of or recycle them. This study aimed to recycle flash-calcined dredged sediment in the development of an eco-friendly 3D-printable mortar. Mortars with 0, 5, 10, 15, 20, and 30% of flash-calcined sediment were studied. Two tests were carried out to determine the printability of the mixtures. First, a manual gun device was used to examine the extrudability, then a modified minislump test was conducted to assess the buildability and shape-retention ability of the mixtures. Furthermore, the flow table test and the fall cone test were used to evaluate the workability and structural buildup, respectively. The compressive strength was also evaluated at 1, 7, and 28 days for printed and nonprinted mortar specimens. In addition, isothermal calorimetry measurements were conducted on corresponding cement pastes. The results showed that it was possible to print mortars with up to 10% of flash-calcined sediment with the preservation of extrudability and buildability. The results showed that flash-calcined sediment shortened the setting time, decreased the flowability, and enhanced the shape-retention ability. Nonprinted samples with 5% and 10% of flash-calcined sediment showed a similar to higher compressive strength compared to that of the reference mortar. However, printed samples recorded an equal to lower compressive strength than that of nonprinted samples. In addition, no significant change in the hydration process was detected for blended cement pastes compared to the reference cement paste

Recycling of Flash-Calcined Dredged Sediment for Concrete 3D Printing

Due to the large volumes of sediments dredged each year and their classification as waste materials, proper management is needed to efficiently dispose of or recycle them. This study aimed to recycle flash-calcined dredged sediment in the development of an eco-friendly 3D-printable mortar. Mortars with 0, 5, 10, 15, 20, and 30% of flash-calcined sediment were studied. Two tests were carried out to determine the printability of the mixtures. First, a manual gun device was used to examine the extrudability, then a modified minislump test was conducted to assess the buildability and shape-retention ability of the mixtures. Furthermore, the flow table test and the fall cone test were used to evaluate the workability and structural buildup, respectively. The compressive strength was also evaluated at 1, 7, and 28 days for printed and nonprinted mortar specimens. In addition, isothermal calorimetry measurements were conducted on corresponding cement pastes. The results showed that it was possible to print mortars with up to 10% of flash-calcined sediment with the preservation of extrudability and buildability. The results showed that flash-calcined sediment shortened the setting time, decreased the flowability, and enhanced the shape-retention ability. Nonprinted samples with 5% and 10% of flash-calcined sediment showed a similar to higher compressive strength compared to that of the reference mortar. However, printed samples recorded an equal to lower compressive strength than that of nonprinted samples. In addition, no significant change in the hydration process was detected for blended cement pastes compared to the reference cement paste

The Development of Soil-Based 3D-Printable Mixtures: A Mix-Design Methodology and a Case Study

Concrete 3D printing is one of the newest technologies in the field of construction. However, despite the various opportunities that this technique offers today, it still has a high environmental impact, as most 3D-printable materials contain high amounts of cement. On the other hand, due to the large volumes of soil excavated each year across the world, there is a pressing need for proper management to dispose of it or reuse it efficiently. This study aims to develop sustainable and resistant 3D-printable materials with low environmental impact using excavated soil. Firstly, a series of tests were carried out to find the most appropriate superplasticizer and the amount required to develop the printable mixtures. Next, the extrudability and buildability were evaluated and verified to validate the printability of the developed mixtures. A 3D laboratory printer was also used to validate the printability of the mixtures on a larger scale. Then, the fresh and hardened properties of the printable mixtures were investigated. Three printable mixtures were developed, with the most environmentally friendly mixture having a soil content of 1602 kg/m3 and a cement content of 282 kg/m3. The mixtures demonstrated satisfactory characteristics and properties in both fresh and hardened states. On the one hand, the mixtures were extrudable and buildable at two laboratory scales. On the other hand, the mixtures presented sufficient compressive strengths, ranging from 16 MPa to 34 MPa, despite their high soil content and low cement content. In addition, their compressive strengths were found to be higher than the minimum strength required for structural concrete. Consequently, this study highlights the possibility of developing ecological, sustainable and resistant mixtures that can be used in 3D-printing construction applications using excavated soil