Recycling NR/SBR waste using probe sonication as a new devulcanizing method; study on influencing parameters

In this work, a vulcanized blend of natural rubber (NR) and styrene butadiene rubber (SBR) (i.e. at weight ratio of 50 : 50) as a model for tire rubber was devulcanized using probe sonication. The effect of processing parameters such as sonication media, power, temperature and time on sol/gel contents and devulcanization percent of rubbery samples was investigated. Moreover, the influence of pre-immersion of vulcanized NR/SBR samples in different liquids (i.e. water, oil and toluene) was assessed for different sonication times (i.e. 10 to 60 min) and powers (i.e. 30 to 60 W). It was found that pre-immersion of rubber particles in oil significantly increased the devulcanization percent. The optimum conditions for devulcanization of the NR/SBR blend via probe sonication were found to be 60 Watts, 20 min, oil and 24 h for sonication power, sonication time, pre-immersion/sonication media and pre-immersion time, respectively. The highest obtained devulcanization percent in this step was about 40%. The effects of two devulcanizing chemical agents (i.e. diphenyl disulfide and VitaX) on devulcanization performances of the samples were also studied. Results showed that higher devulcanization percent (i.e. about 52%) was obtained by using VitaX. It was also observed that VitaX significantly improved re-vulcanization speed (i.e. cure rate index) and decreased scorch time. It was also found that lower content of VitaX (i.e. 0.6 phr) caused better curing properties but lower mechanical properties compared to the higher content (i.e. 1.2 phr).

In this work, a vulcanized blend of natural rubber (NR) and styrene butadiene rubber (SBR) (i.e. at weight ratio of 50 : 50) as a model for tire rubber was devulcanized using probe sonicationP.     

Vascular aneurysms in Ehlers-Danlos syndrome subtypes: A systematic review

Aneurysmal lesions are commonly seen in Ehlers-Danlos Syndrome (EDS). To better identify the regional and vessel-specific spectrum of aneurysms in different subtypes of EDS, we performed a systematic review. We searched Medline for relevant studies from 1963 to April 2022. Studies providing a report of any EDS subtype by genetic diagnosis, histologic analysis, or clinical criteria were included. A total of 448 patients from 220 studies were included. 720 vessel-specific aneurysms were reported: 386 in the abdominopelvic area, 165 in the intracranial region, 98 in the thorax, 2 in the extremities, and 6 in the venous system. In 27 out of the 65 patients with ruptured aneurysms, the ruptured aneurysm was the initial presentation. Multiple aneurysms were present in 163 out of 249 patients who had been systematically evaluated for other locations of aneurysms. The head and neck and abdominopelvic regions are two potential foci for aneurysm formation in patients with EDS. The aneurysm development in EDS is not confined to arteries; the venous system and cardiac septa may also be affected. Many patients develop multiple aneurysms, either at the time of the initial presentation or throughout their lifetime and aneurysm formation or rupture may be the first presentation of EDS.     

Wilms tumor treatment protocol compliance and the influence on outcomes for children in Tanzania

Background

Standardized Wilms tumor treatment protocols exist for low- and middle-income countries, but outcomes equivalent to high-income countries are not achieved outside of clinical trials. As Wilms tumor treatment protocols in Africa shift with increasing resource capacity, it is not known how treatment compliance to each stage of therapy affects outcomes and where the critical breakpoints are for protocol adherence in clinical practice.

Procedure

We describe both treatment outcomes and treatment protocol adherence in a retrospective single-center cohort study of pediatric Wilms tumor patients at a zonal cancer referral hospital in Tanzania from 2016 to 2019, treated per the International Society of Paediatric Oncology standard (2016–2017) or Tanzania adapted (2018–2019) therapy protocols.

Results

A total of 69 patients were evaluated. The two-year overall survival and event-free survival rates were 40% and 29%, respectively. Only 29% of patients completed recommended chemotherapy per protocol, and completion of preoperative and postoperative chemotherapy was predictive of two-year overall survival (odds ratio [OR] 14.4, p < .001). There were delays at almost every stage of treatment, especially time from preoperative chemotherapy to surgery (56 days), from surgery to pathology report (30 days), and from surgery to initiation of postoperative chemotherapy (38 days).

Conclusions

Nonadherence with recommended Wilms tumor treatment guidelines due to key health system delays correlated to reduced overall survival rates, with chemotherapy nonadherence due to abandonment, lack of surgery, and deaths on therapy as the strongest contributors. Future interventions targeting health system delays and reducing deaths during therapy are critical to improving protocol compliance and increasing overall survival for pediatric Wilms tumor patients in low-resource settings.