123,109 research outputs found
Fabrication and environmental applications of glass microspheres: A review
No full textContinuous technological progress is required to improve production efficiency and environmental quality while maintaining economic competitiveness. A non-negligible contribution to some of these goals can be achieved through the production of glass microspheres for a wide range of applications. The fabrication techniques of glass microspheres including flame synthesis, liquid droplet method, dried gel process and electrical arc process are surveyed. The mechanisms of the recent syntheses of porous and hollow glass microspheres are also reviewed. Glass microspheres are a promising substrate for titania coatings which can be used in water purification and self-cleaning systems. Due to their high mechanical strength and low thermal conductivity, they can also be applied in cementitious and insulating products. Glass microspheres can carry hydrogen gas at pressures of up to 150 MPa. In addition, they can enhance the quality of lead-acid batteries by decreasing the critical volume fraction..
Advanced Dye Sorbents from Combined Stereolithography 3D Printing and Alkali Activation of Pharmaceutical Glass Waste
No full textAdditive manufacturing (AM) technologies enable the fabrication of objects with complex geometries in much simpler ways than conventional shaping methods. With the fabrication of recyclable filters for contaminated waters, the present work aims at exploiting such features as an opportunity to reuse glass from discarded pharmaceutical containers. Masked stereolithography-printed scaffolds were first heat-treated at relatively low temperatures (680 and 730 °C for 1 h) and then functionalized by alkali activation, with the formation of zeolite and sodium carbonate phases, which worked as additional adsorbing centers. As-sintered and activated scaffolds were characterized in terms of the efficiency of filtration and removal of methylene blue, used as a reference dye. The adsorption efficiency of activated printed glass was 81%. The 3D-printed adsorbent can be easily separated from the solution for reuse
Enhanced methylene blue adsorption by double alkali activation of highly porous glass microspheres prepared from waste glass
No full textThe remediation of water from organic pollutants, such as dyes and related compounds and the reuse of discarded glasses, represents fundamental challenges in highly industrialized countries. Porous glass microspheres have been proposed as efficient adsorbents in wastewater treatment, but their real application is problematic, especially from the perspective of their reuse and recycling. For the first time, the present paper describes the process of preparation and use of highly porous bodies with a specific surface area of nearly 20 m2/g fabricated from alkali activated glass microspheres and applicable for the removal of methylene blue as a model organic dye from wastewater. Alkali activation is applied both as an intermediate step (using 9 M KOH) for the conversion of waste glass into porous microspheres by flame spheroidization process, and as a final step (using 2.5 M NaOH), facilitating low temperature consolidation of the microspheres, and their transformation into porous structures. The experimental adsorption capacity of porous glass microspheres pellet was 122 mg/g. The high correlation coefficient indicates the applicability of Langmuir isotherm adsorption model
sj-docx-1-mde-10.1177_23821205241227327 - Supplemental material for Perceptions and Experiences of Pursuing Research Among Medical Students in Problem-Based Learning Curriculum: A Cross-Sectional Study from Qatar
No full textSupplemental material, sj-docx-1-mde-10.1177_23821205241227327 for Perceptions and Experiences of Pursuing Research Among Medical Students in Problem-Based Learning Curriculum: A Cross-Sectional Study from Qatar by Reem R Al-Subai, Muhammad Z Kaleem, Doaa Hassanien, Meral Eldestawy, Mahmoud N Hamwi, Engy Elsayed, Amal S Al-Kawari, Habib H Farooqi and Suhad Daher-Nashif in Journal of Medical Education and Curricular Development</p
Upcycling waste derived glass into high-performance photocatalytic scaffolds by alkali activation and direct ink writing
No full textNovel and eco-friendly solutions are extensively needed for wastewater treatment. This work capitalizes on the combination of waste vitrification and additive manufacturing to produce an efficient photocatalyst for the specific purpose. Fine powders of waste-derived glass, containing Fe3O4 inclusions, by simple suspension (for a solid loading of 65 wt %) in alkaline solution (5 M NaOH), were transformed into pastes for direct ink writing. 3D-printed reticulated scaffolds were stabilized by the progressive hardening of a zeolite-like gel, formed by glass/solution interaction, at nearly room temperature. The printed scaffolds were successfully tested for the removal of methylene blue, realized by combining the high sorption capacity of the gel with the catalytic activity of magnetite inclusions, under UV light. A complete degradation of methylene blue is achieved by 90 min exposure, comparing favorably with other reported photocatalytic materials, requiring from 60 to 360 min. The photocatalytic activity was tested for several cycles, with no significant degradation. In other words, a waste-derived material can be reused for multiple times, to remediate wastewaters, with evident benefits on waste minimization
Alkali activation-induced cold consolidation of waste glass: Application in organic-free direct ink writing of photocatalytic dye destructors
No full textAdditive manufacturing, with its ability to assemble a variety of materials in complex and customized architectures, is developing rapidly. The integration of technologies and materials into a sustainable production, however, is still challenging. The present investigation offers new functional glass-based products, from nearly room temperature processing, based on direct ink writing (DIW) of pastes from ‘light’ alkali activation (2.5 M NaOH) of pharmaceutical glass waste, added with 20 wt% of TiO2 nanoparticles. The inks were refined by the inclusion of porous glass microspheres (PGMs, 20–30 wt%), previously fabricated from fiber glass waste. Printed scaffolds, stabilized by simple drying (i.e. ‘unfired’), were successfully applied in the photodegradation of methylene blue. The degradation efficiency reached 100% within 75 min, and the 3D-printed composites could be easily separated from the solution for subsequent reuse. The degradation efficiency declined only by 7.5%, after 5 cycles
sj-pdf-2-mde-10.1177_23821205241227327 - Supplemental material for Perceptions and Experiences of Pursuing Research Among Medical Students in Problem-Based Learning Curriculum: A Cross-Sectional Study from Qatar
No full textSupplemental material, sj-pdf-2-mde-10.1177_23821205241227327 for Perceptions and Experiences of Pursuing Research Among Medical Students in Problem-Based Learning Curriculum: A Cross-Sectional Study from Qatar by Reem R Al-Subai, Muhammad Z Kaleem, Doaa Hassanien, Meral Eldestawy, Mahmoud N Hamwi, Engy Elsayed, Amal S Al-Kawari, Habib H Farooqi and Suhad Daher-Nashif in Journal of Medical Education and Curricular Development</p
Direct Ink Writing of AISI 316L Dense Parts and Porous Lattices
No full textThe focus of the present work is the development of a metallic ink that possesses controlled rheological properties: by keeping printing parameters constant both AISI 316L dense parts and porous scaffolds have been produced. Shrinkage, porosity, and mechanical properties have been studied to evaluate the link between the ink rheological properties and the final part. Depending on binder composition, linear shrinkage ranging from 9% to 22% and porosity from 34 to 7 vol% are measured. Tensile strength for specimens sintered at 1240 °C reach the value of 444 MPa and elongation at a break of 12.3%. These values are still far from additively manufactured AISI 316L parts with powder bed fusion technologies, but represent an improvement compared to previously reported data in the literature for AISI 316L parts 3D printed by DIW. Porous scaffolds with a spanning distance of 1.2 mm are printed and sintered. Porosity of 74 vol% and compression strength of 74 MPa are measured for this set of samples showing how the produced ink represents a valuable alternative to pastes already present in the literature
A Deduced Method for Assessing Safety and Security Perception: Case Study of Biblioteca Degli Alberi Park in Milan, Italy
No full textUrban greening initiatives have taken many innovative forms over time, from large urban parks planning and preservation to ecosystem-based approaches such as Nature-based Solutions (NBS). Even though implementing NBS and vegetation are accompanied mainly by positive impacts, a considerable body of scientific evidence demonstrates the negative consequences of urban green areas on the subject of reducing safety and safety perception in terms of impacts on visibility and fear of crime. Considering vegetation as a critical element of the urban landscape, identifying the safety perception while implementing greenery interventions requires a deep study of their characteristics about space functionality.
This chapter aims to implement a methodology for assessing the safety and security perception of urban green spaces. The methodology is based on safety and security principles and indicators selected from an extensive literature review of scientific research and design guidelines for safer cities and relying in particular on the concept of Crime Prevention Through Environmental Design (CPTED). Assembling data regarding the case study’s safety perception is conducted through a survey-based approach and an online questionnaire. Case-study application for testing the methodology was the Biblioteca degli Alberi di Milano (BAM) park in Milan, Italy
Nature-Based Solutions for Resilient and Thriving Cities: Opportunities and Challenges for Planning Future Cities
No full textThis chapter explains the importance for nature-based solutions as resilience
infrastructure of cities. It sets the scene for the challenges and opportunities
presented by a city-wide uptake and implementation of nature-based solutions as
integrative and systemic solutions to planning for urban resilience and sustainability.
We present not only the origins and the reasons for preferring nature-based solutions
over conventional grey infrastructure for dealing with climate change pressures
but also how different planning aspects of nature-based solutions need to be reconsidered,
reimagined and thereafter, transformed. In conclusion, an outlook towards
future cities is given on revolutionizing urban planning practice through naturebased
solutions
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