No abstract

The dismantling and disposal of electronic waste (e-waste) in developing countries is causing increasing concern because of its impacts on the environment and risks to human health. Heavy-metal concentrations in the surface soils of Guiyu (Guangdong Province, China) were monitored to determine the status of heavy-metal contamination on e-waste dismantling area with a more than 20 years history. Two metalloids and nine metals were selected for investigation. This paper also attempts to compare the data among a variety of e-waste dismantling areas, after reviewing a number of heavy-metal contamination-related studies in such areas in China over the past decade. In addition, source apportionment of heavy metal in the surface soil of these areas has been analysed. Both the MSW open-burning sites probably contained invaluable e-waste and abandoned sites formerly involved in informal recycling activities are the new sources of soil-based environmental pollution in Guiyu. Although printed circuit board waste is thought to be the main source of heavy-metal emissions during e-waste processing, requirement is necessary to soundly manage the plastic separated from e-waste, which mostly contains heavy metals and other toxic substances.

No abstract

During minimally invasive orthopedic surgeries, surgical intervention is required at two stages; to attain hemostasis and subsequently to implant the bone graft or its substitute. There is an apparent need for a material which can simultaneously control bone bleeding and provide support for bone repair. In this work, a moldable putty, which can be applied to bone defects (usually irregular in shape), was developed to address this need. It comprises of a hemostatic factor thrombin, osteoinductive "yolk-shell" particles containing bone growth factor (BMP-2), and an osteoconductive component hydroxyapatite. The yolk shell particles allowed controlled release of BMP-2 and showed significantly enhanced osteogenic differentiation of C2C12 (mouse myoblast) cells as demonstrated by increased alkaline phosphatase (ALP) activity and relative gene expressions of osteogenic differentiation markers. These particles were assembled into a moldable putty by mixing them with hydroxyapatite and silk fibroin solution (binding agent) supplemented with thrombin. The putty showed non-cytotoxicity, hemostatic ability, sustained release of BMP-2 and induced increased mineralization in C2C12 cells. This putty, if applied to bone defects during surgeries, may help attain hemostasis and may enhance bone repair by providing sustained release of bone growth factors.

Robot-assisted technology is often used to perform endovascular catheterization surgeries, which generally depend on the flexible operability and the accurate force feedback of a robotic system. In this paper, an endovascular catheterization robotic system (ECRS) was developed to improve collaborative operation and haptic force feedback. A couple of operating handles were designed to maximize the use of the natural operations of surgeons on the master side, which is a flexible and ergonomic device. A magnetically controlled haptic force feedback structure is proposed based on hydrogel and solid magnetorheological (MR) fluid to offer a sense of haptic feedback to operators; this has potential influence on the field of force feedback. In addition, a unique tremor-reduction structure is introduced to enhance operating safety. Tracking performance experiments and in vitro experiments were conducted to evaluate the performance of the developed ECRS. According to these experimental results, the average translation-tracking error is 0.94 mm, and the average error of rotation is 0.89 degrees. Moreover, in vitro experiments demonstrated that haptic feedback has the advantage of reducing workload and shortening surgery completion time. The developed ECRS also has the benefits of inspiring other researchers to study collaborative robots and magnetically controlled feedback.