Impact of salinity gradient, water pollution and land use types on greenhouse gas emissions from an urbanized estuary.

Estuaries have been recognized as one of the major sources of greenhouse gases (GHGs) in aquatic systems; yet we still lack insights into the impact of both anthropogenic and natural factors on the dynamics of GHG emissions. Here, we assessed the spatiotemporal dynamics and underlying drivers of the GHG emissions from the Scheldt Estuary with a focus on the effects of salinity gradient, water pollution, and land use types, together with their interaction. Overall, we found a negative impact of salinity on carbon dioxide (CO2) and nitrous oxide (N2O) emissions which can be due to the decrease of both salinity and water quality when moving upstream. Stronger impact of water pollution on the GHG emissions was found at the freshwater sites upstream compared to saline sites downstream. In particular, when water quality of the sites reduced from good, mainly located in the mouth and surrounded by arable sites, to polluted, mainly located in the upstream and surrounded by urban sites, CO2 emissions from the sites doubled while N2O emissions tripled. Similarly, the effects of water pollution on methane (CH4) emissions became much stronger in the freshwater sites compared to the saline sites. These decreasing effects from upstream to the mouth were associated with the increase in urbanization as sites surrounded by urban areas released on average almost two times more CO2 and N2O than sites surrounded by nature and industry areas. Applied machine learning methods also revealed that, in addition to salinity effects, nutrient and organic enrichment stimulated the GHG emissions from the Scheldt Estuary. These findings highlight the importance of the interaction between salinity, water pollution, and land use in order to understand their influences on GHG emissions from dynamic estuarine systems.

Lateral-Opening Injection Tool Used in Percutaneous Vertebroplasty to Treat Asymptomatic Osteoporotic Vertebral Burst Fractures: A Retrospective Study.

OBJECTIVE: The adequate management of asymptomatic osteoporotic vertebral burst fractures (OVBFs) was still controversial. Percutaneous vertebroplasty (PVP) could achieve quick recovery with minor trauma, but there were certain safety problems by traditional bone cement injection method. Thus, the aim of this study was to assess the efficacy of lateral-opening injection tool used in PVP treating patients with asymptomatic OVBFs. METHODS: This was a retrospective study of OVBFs treated in our institute from March 2016 to March 2020. A total of 66 patients (mean age 72.10 ± 7.98 years, with 21 men and 45 women) who were diagnosed with acute asymptomatic OVBFs with mild spinal canal compromise were treated with PVP by using a lateral-opening injection tool. Two puncture needles were simultaneously placed transpedicularly in the fractured vertebra, and the inner core was removed, and the lateral-opening injection tool was inserted. The adjustment of lateral hole was to improve the distribution height of bone cement and avoid the entry of bone cement into the posterior wall of vertebral body. Related clinical outcomes and images were assessed, including back pain (visual analog scale [VAS]), vertebral height ratio (fractured vertebral height/average adjacent nonfractured vertebral height), kyphosis Cobb angle, union of the fractured vertebral posterior wall, distribution of bone cement, surgical data, and complications. RESULTS: The average follow-up time of all cases was 21.23 ± 9.35 months. The mean amount of bone cement was 3.28 ± 0.35 ml in the vertebrae and the mean operative time was 34.02 ± 5.23 min. There were 60 cases of bone cement that contacted the upper and lower endplates on at least one side. There was no cement leakage into the spinal canal or fracture displacement of the posterior wall of the vertebral body in all cases. The VAS scores were 3.78 ± 0.42 at 1 day postoperatively and 0.53 ± 0.40 at the last follow-up, significantly lower than 8.40 ± 0.48 preoperatively (p < 0.05). The average height ratio of anterior, middle, and posterior vertebral body after operation increased compared with that pre-operation (p < 0.05), and the postoperative kyphosis angle decreased (p < 0.05). At 6 months follow-up, there was no significant height loss of the vertebral body. Computed tomography examination 3 months postoperatively showed that the fracture of posterior vertebral wall healed well in all cases. There were seven cases of bone cement leakage without clinical symptoms and two adjacent vertebral fractures caused by falling. There were no cases of deep vein embolism, lower limb muscle atrophy, pneumonia, decubitus. CONCLUSION: The lateral opening tool can be safely and effectively used in the PVP treatment on asymptomatic OVBFs with mild spinal canal compromise.

Bioactive injectable polymethylmethacrylate/silicate bioceramic hybrid cements for percutaneous vertebroplasty and kyphoplasty.

Polymethylmethacrylate (PMMA) cement has been widely used to fill and stabilize hard tissue defects in clinical surgery, especially in percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP). However, the dense body of pure PMMA in defects has no ability to promote bone regeneration. We herein aim to fabricate novel PMMA/silicate bioceramic hybrid cements by adding bioactive calcium silicate (CS) particles into PMMA to endow PMMA/CS hybrid cements with bioactivity and biodegradability without losing the excellent mechanical strength and injectability. Following comprehensive characterization of the physicochemical properties and in vitro bioactivity study, our results showed compared with PMMA cement, the constructed PMMA/CS hybrid cements possessed significantly lower curing temperatures and simultaneously retained the acceptable mechanical strength and injectability. Moreover, obvious bioactive ion release and hydroxyapatite formation could be detected and observed after the PMMA/CS hybrid cements were soaked in simulated body fluid, indicating their pronounced bioactivity. A further in vivo study of the PMMA/CS hybrid cements on goat vertebral body defect models reflected that the PMMA/CS hybrid cements could be biodegraded well and could significantly promote new bone formation in defects 6 months of post-injection. Our results suggest that PMMA/CS hybrid cements may be promising candidates for PVP and PKP in clinic.