A sustainable acoustic customization of open porous materials using recycled plastics

Foams are commonly used as sound absorbers and thermal insulators for many industrial and construction applications. The insulating materials market is currently dominated by inorganic fibres like glass and mineral wool, as well as plastic foams. However, worldwide plastics consumption produces huge amounts of waste, generating concerns about soil, air and especially seawater pollution. Hence, new methods for recycling marine microplastic litter according to cleaner production criteria are being sought. This paper presents a novel, sustainable and eco-friendly foamy material made of microplastic waste, namely polyethylene terephthalate (PET) and polystyrene (PS), incorporated into a bio-based matrix. Samples with different compositions were prepared and then characterized for sound absorption properties. Evidence is presented of very good acoustic performances and of how the acoustic characteristics of the end product can be customized using different microplastic content and type. This allows envisioning many industrial and civil applications for this novel open-cell material.

Indoor and outdoor noise changes due to the COVID-19 lockdown and their effects on individuals' expectations and preferences

The COVID-19 pandemic significantly modified our urban territories. One of the most strongly affected parameters was outdoor noise, caused by traffic and human activity in general, all of which were forced to stop during the spring of 2020. This caused an indubitable noise reduction both inside and outside the home. This study investigates how people reacted to this new unexpected, unwanted and unpredictable situation. Using field measurements, it was possible to demonstrate how the outdoor sound pressure level clearly decreased. Furthermore, by means of an international survey, it was discovered that people had positive reaction to the lower noise level. This preference was generally not related to home typology or location in the city, but rather to a generalized wish to live in a quieter urban environment.

How much COVID-19 face protections influence speech intelligibility in classrooms?

The ongoing pandemic caused by the COVID-19 virus is challenging many aspects of daily life. Several personal protective devices have become essential in our lives. Face protections are mostly used in order to stop the air aerosol coming out of our mouths. Nevertheless, this fact may also have a negative effect on speech transmission both in outdoor and indoor spaces. After a severe lockdown, classes have now started again. The adoption of face protection by teachers is either recommended or mandatory even though this is affecting speech intelligibility and thus students' comprehension. This study aims to understand how protections may affect the speech transmission in classrooms and how this could be influenced by the several typologies of face protections. An experimental campaign was conducted in a classroom in two different reverberant conditions, measuring and comparing the variation in speech transmission and sound pressure level at different receiver positions. Furthermore, a microphone array was used to investigate the distribution of the indoor sound field, depending on the sound source. Results clearly show how different types of personal protection equipment do affect speech transmission and sound pressure level especially at mid-high frequency and that the source emission lobes vary when wearing certain types of personal devices.

Combined effects of environmental factors on human perception and objective performance: A review of experimental laboratory works

This study reports the outcomes of a literature survey aimed at exploring how different environmental factors-that is acoustic, thermal, visual, and air quality stimuli-interact in affecting building occupants' perception and performance. Recent laboratory studies have been collected, and their methodological approaches reviewed in terms of experimental design, adopted exposures conditions, perception and performance assessment methods. Results have been summarized and compared to identify interaction patterns between environmental factors and possible practical implications for improving the design of both experimental studies and the built environment. The analysis allows highlighting limitations, potential improvements and future opportunities in this field of research, thus providing a reference for further investigations aimed at a deeper understanding, modeling, and prediction of the impacts caused by the main indoor variables on human comfort and performance.

Repair of distal biceps tendon acute ruptures with two suture anchors and anterior mini-open single incision technique: clinical follow-up and isokinetic evaluation

BACKGROUND

All the techniques described in literature for treatment of acute distal biceps tendon ruptures provide good functional outcomes. The purpose of this study is to report the results of a single limited-incision technique for repair of acute distal biceps ruptures using two suture anchors.

MATERIALS AND METHODS

Fourteen patients, all man, were treated consecutively from one author between January 2009 and December 2011 and evaluated at a mean follow-up of 26 months. All patients were evaluated clinically, through DASH and MEPS score questionnaires, and with isokinetic biomechanical tests.

RESULTS

All patients achieved complete elbow flexion and extension. Deficit for supination of the forearm was found in only two patients (7° and 13°). Mean DASH score was 4.7 points, and mean MEPS was excellent (96.8 points). There was no nervous complication involving posterior interosseous nerve (PIN) and no case of failure of the sutures. The isokinetic evaluation detected an average flexion strength increase by 10.2 % compared to the opposite arm not operated.

CONCLUSION

Our study shows that mini-open access and fixation with two suture anchors achieved in medium-term excellent functional and cosmetic results needed short rehabilitation times and is minimally invasive.