Removal of ammonium from wastewater with geopolymer sorbents fabricated via additive manufacturing

Geopolymers have been recently explored as sorbents for wastewater treatment, thanks to their mechanical and chemical stability and to their low-energy manufacturing process. One specific application could be the removal of ammonium (NH4+) through exchange with Na+ ions. Additive manufacturing (AM) represents an especially interesting option for fabrication, as it allows to tailor the size, distribution, shape, and interconnectivity of pores, and therefore the access to charge-bearing sites. The present study provides a proof of concept for NH4+ removal from wastewater using porous geopolymer components fabricated via direct ink writing (DIW) AM approach. A metakaolin-based ink was employed for the fabrication of a log-pile structure with 45\ub0 rotation between layers, producing continuous yet tortuous macropores which are responsible for the high permeability of the sorbents. The ink consolidates in an amorphous, mesoporous network, with the mesopores acting as preferential sites for ion exchange. The printed sorbents were characterized for their physicochemical and mechanical properties and the NH4+ removal capacity in continuous-flow column experiments by using a model effluent. The lattices present high permeability and high cation exchange capacity and maintained a high amount of active ions after four cycles, allowing to reuse them multiple times

Implant supported cantilevered fixed dental rehabilitations in partially edentulous patients : systematic review of the literature. Part I

Objectives: To investigate in which clinical situations a cantilever fixed implant supported restorations can be a treatment alternative and which complications are reported. Materials and Methods: Two operators screened the literature (MEDLINE, EMBASE) and performed a hand search on the main journals dealing with implantology and prosthetics until 31 December 2017. Only articles that considered cantilever implant fixed restorations with at least 10 patients and with a mean follow-up of at least 5\ua0year were selected. The outcome variables were survival of implants and prosthesis, mechanical, technical and biological complications, marginal bone loss. The review was performed according to the PRISMA statements. Risk of bias assessment was evaluated. Failure and complication rates were analysed using random effect Poisson regression models to obtain summary estimate of 5- and 10-year survival and complication rates. Results: A total of nine papers were selected for partially edentulous patients and reported high survival rate of the prosthesis. The estimated survival rate for 5\u201310\ua0years was calculated to be 98.4% for the implants and 99.2% for the rehabilitations. Mechanical, technical and biological complications were reported with a cumulative 5\u201310\ua0years complication rate of 28.66% and 26.57% for the patients and for the prosthesis, respectively. Two papers for single implant supporting 2-unit cantilever were not sufficient to draw conclusions. Conclusions: There is evidence that cantilever can be successful treatment in partially edentulous patients. In two adjacent edentulous sites, data are not yet sufficient

Identification of most relevant variables and processes to assess the environmental impacts of remediation technologies along their life cycles: Focus on the waste management scenarios

The application of Life Cycle Assessment (LCA) to remediation technologies is still not a consolidated practice and it is especially lacking in the assessment of the environmental impacts associated to the management of the waste produced during remediation. This study aims at addressing these methodological gaps by identifying the typologies of waste typically generated during the remediation of a contaminated site and classifying them according to the European Waste Catalogue (EWC) codes. Thereafter, the following steps are: (i) the identification of the waste management scenarios (WMSs) applicable to the identified waste typologies, (ii) the selection of Life Cycle Assessment processes that can be used to assess the impacts of the different WMSs and (iii) the quantification and comparison of the environmental impacts caused by the different WMSs applied considering hazardousness levels to which the same waste may belong in relation to its contamination levels and characteristics: inert, non-hazardous and hazardous waste (Waste Framework Directive 2008/98/EC). As results, a matrix reporting the classes and typologies of waste, their EWC codes, their different WMSs and the suitable LCA processes from the Ecoinvent database that can be applied to each EWC within a specific WMS, has been developed. Additionally, the comparative assessment of the impacts caused by the Ecoinvent processes applicable to the same waste typology within the same WMS has been performed to support the selection of the most appropriate WMS case by case

Stratification of prosthetic complications by manufacturer in implant-supported restorations with a 5 years’ follow-up: systematic review of the literature

INTRODUCTION: Prosthetic complications on implant-supported restorations have been documented in several papers published in the literature. Several manufacturers are present on the market but results are often cumulated and may thus be misleading. The objective of the present review is to assess the prosthetic complications of implant-supported restorations with particular interest of the results obtained with prostheses from different manufacturers. EVIDENCE ACQUISITION: A manual search of Medline/PubMed was carried out up to June 2016, yielding a total of 6832 articles, which were narrowed down to 1450, then 347 abstracts to include 55 papers after full text reading. Papers with at least 5 years of follow-up reporting on prosthetic complications of single and fixed partial prosthesis were included. Prosthetic complications were divided into mechanical and technical complications, and reported in a table. EVIDENCE SYNTHESIS: Overall 14.4% of prosthetic complication was found for a total of 6623 restorations followed for an average of 7.4 years (range 5-16 years). Results where then sorted and compared. Single crowns were affected by 1.4% of mechanical complications and 10.9% of technical complications after a mean of 7.4 years. Fixed partial prosthesis were affected by 2.5% of mechanical complications and 18% of technical complications. Screw-retained and cemented restorations were calculated to have a 5 years rate of complications of 21.2% and 9.3%, respectively, which demonstrated a statistically difference with fisher exact test with P<0.1. Only 3 manufacturers presented more than 10 articles and were directly compared with Fisher's exact test with P<0.1. The incidence of overall complications was estimated to be after 5 years of 11.2%, 10.8% and 13.8% for Straumann, Nobel, and Astratech, respectively, but dividing results in mechanical and technical complications, gave different results. Straumann was estimated to have less mechanical complications after 5 years in respect to Nobel and Astratech, but the three were similar for technical complications. CONCLUSIONS: although studies present very different material and methods and do not report all data, some conclusions can be made. The difference between mechanical complications lead the authors to suppose that there might be a difference in results obtained by different implant abutment connections. It is also noticed that all papers were published by expert clinicians and universities research centers that apply rigid surgical and prosthetic protocols and use original abutments

Six-mm versus 10-mm long implants in the rehabilitation of posterior edentulous jaws : a 5-year follow-up of a randomised controlled trial

To compare the clinical outcome of 6-mm and 10-mm long implants in partially edentulous posterior areas. MATERIALS AND METHODS: Twenty-four patients, with a partially edentulous area in the jaws with a height and width allowing the positioning of 2 to 3 adjacent 10 7 4.1 mm implants without any augmentation procedure, were randomly allocated according to a parallel group design to receive 6-mm long or 10-mm long implants. A total of 54 implants were placed (26 7 6 mm and 28 7 10 mm implants). Patients were restored 8 weeks after surgery and were followed for 5 years. Outcome measures were prosthesis and implant survival, as well as marginal bone level changes and complications. RESULTS: After 5 years, 18 patients were available. One 6 mm implant failed during the healing period and its related prosthesis could not be placed. No implants were lost after loading. The 6 mm group registered 5 complications (1 mucositis, 3 prosthesis decementations and 1 chipping), while only 3 were registered in the 10 mm group (2 decementations and 1 chipping). The difference in complications between the two groups was not statistically significant (P = 0.39). Marginal bone loss at 5 years was 0.43 and 0.24 mm with the 6 mm and 10 mm groups, respectively (not statistically significant; difference between the two groups 0.19 mm; SD 0.23 mm; 95% CI -0.34;0.73; t test P = 0.42) CONCLUSIONS: Implant and prosthetic survival and success rates were similar between prostheses supported by 6-mm or 10-mm long implants. Conflict-of-interests statement: The present study was supported by grant 369_2004 from ITI, Basel, Switzerland used to provide free implants and prosthetic components to the patient. Authors declare no conflict of interest