Odour characterisation of recycled HDPE in different washing and processing processes.

The waste of polymeric materials in our society is increasing year after year, generating a serious pollution problem. One way to deal with this waste problem is to recycle and reuse these materials. This process of recovery of used plastic materials aims to minimise their impact on the environment and reduce the energy consumption required for the generation of new consumer products. Recycling companies that recover these plastic materials must take into account some aspects such as transparency and colour, cleanliness, size, odour and sorting. One of the major disadvantages in accepting these recycled materials in the production processes is their odour, which in some cases causes the rejection of materials with comparable mechanical characteristics. High-density polyethylene, HDPE, is one of the polymeric wastes generated in the packaging industry. The aim of this work is to eliminate the bad odour of HDPE from waste collection plants for application in the recovery and reuse industry. HDPE supplied by a recycling company was washed, characterised and processed, and the odour was analysed by gas chromatography at each stage and by olfactory panel. In view of the results, it was observed that the washing processes managed to reduce the odour. Likewise, the processing of this waste by extrusion and injection managed to further reduce this effect, even eliminating some of the components responsible for odour by treating the samples with acetone and then extruding and injecting these samples. These results have a direct application in the packaging industry with significant shares of recycled material.

International Alliance of Urolithiasis guideline on retrograde intrarenal surgery.

OBJECTIVES: To set out the second in a series of guidelines on the treatment of urolithiasis by the International Alliance of Urolithiasis that concerns retrograde intrarenal surgery (RIRS), with the aim of providing a clinical framework for urologists performing RIRS. MATERIALS AND METHODS: After a comprehensive search of RIRS-related literature published between 1 January 1964 and 1 October 2021 from the PubMed database, systematic review and assessment were performed to inform a series of recommendations, which were graded using modified GRADE methodology. Additionally, quality of evidence was classified using a modification of the Oxford Centre for Evidence-Based Medicine Levels of Evidence system. Finally, related comments were provided. RESULTS: A total of 36 recommendations were developed and graded that covered the following topics: indications and contraindications; preoperative imaging; preoperative ureteric stenting; preoperative medications; peri-operative antibiotics; management of antithrombotic therapy; anaesthesia; patient positioning; equipment; lithotripsy; exit strategy; and complications. CONCLUSION: The series of recommendations regarding RIRS, along with the related commentary and supporting documentation, offered here should help provide safe and effective performance of RIRS.

Clinical performance of alveolar ridge augmentation with xenogeneic bone block grafts versus autogenous bone block grafts. A systematic review.

INTRODUCTION: This systematic literature review aimed to evaluate the feasibility of xenogeneic bone blocks for ridge augmentation compared with autogenous blocks by analyzing block survival rates, block resorption, subsequent implant survival rate, post-surgical complications, and histomorphometric findings. MATERIALS AND METHODS: Electronic searches were conducted in the Medline (PubMed), Web of Science and Cochrane databases, complimented by a manual search in specialist journals, for relevant articles published up to March 2020. Inclusion criteria were human studies in which the outcomes of xenogeneic bone block grafts were evaluated by means of their survival rates and subsequent implant survival rates. RESULTS: Sixteen articles fulfilled the inclusion criteria and were analyzed. 333 patients were recruited with a total of 337 xenogeneic bone blocks and 82 autogenous bone blocks, showing block failure rates of 6.82% and 6.1%, respectively. Bone gain, in both height and width, was similar among xenogeneic and autogenous bone blocks, but autogenous bone blocks suffered greater resorption. Implant survival rates were slightly lower for xenogeneic bone blocks. Histological and histomorphometric analysis observed more bone formation and less residual bone substitute with autogenous bone blocks than xenogeneic bone blocks. CONCLUSIONS: Atrophic alveolar crest reconstruction with xenogeneic bone block grafts would appear to offer a viable alternative to autogenous bone block grafts, obtaining similar block graft failure rate, fewer sensitive postoperative complications but a slightly lower implant survival rate. Further investigations generating long term data are needed to confirm the feasibility of xenogeneic bone blocks in different clinical scenarios.