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Selenium
SodiuSelenium is a chemical element with symbol Se and atomic number 34.[1] It is an odourless metalloid (an element which has both metallic and non-metallic properties). It can be a grey (the ‘metallic’ and most stable form), red or black solid. [2] In nature selenium is usually combined with sulphide minerals or with silver, copper, lead, and nickel. [3]
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Featured Articles
APVMA announces chemical review of neonicotinoids
The Australian Pesticides and Veterinary Medicines Authority (APVMA) has announced a chemical review of a group of systemic insecticides known as the neonicotinoids. Based on possible risks, including to pollinators, aquatic invertebrates, birds and small mammals, the reassessment will be environment-focussed. The review will also consider whether product labels carry adequate instructions to protect community and worker health. “This reconsideration will allow us to reassess the risks posed by neonicotinoid use, and whether any regulatory changes are necessary to protect the health and safety of people, animals, plants, and the environment. “There has been a lot of global regulatory interest in neonicotinoids and a number of reports linking neonicotinoids with adverse environmental impacts, including on aquatic health and nontarget and terrestrial invertebrates.” said the APVMA Chief Executive Officer, Dr Chris Parker. “There is also a need to ensure our approved labels align with recently published APVMA guidelines (including for pollinators and managing spray drift).” The APVMA and the New Zealand Environmental Protection Agency (NZ EPA) plan to work together to identify areas of possible collaboration over the course of this review. “While NZ EPA and APVMA have their own legislative frameworks to operate under, this is an opportunity for the agencies to work together in a collaborative manner to achieve efficiencies that best serve our roles as chemical regulators both in Australia and New Zealand.” said Dr Parker. The first stage of the review will seek public comment on the scope and work plan, which is available in the Gazette. Submissions will close on 3 February 2020. More information on the review is available on the APVMA website.
https://www.apvma.gov.au/
Stretchable, degradable semiconductors
To seamlessly integrate electronics with the natural world, materials are needed that are both stretchable and degradable — for example, flexible medical devices that conform to the surfaces of internal organs, but that dissolve and disappear when no longer needed. However, introducing these properties to electronics has been challenging. Now, researchers reporting in ACS Central Science have developed stretchable, degradable semiconductors that could someday find applications in health and environmental monitoring. Semiconductors, which are essential components of almost all computers and electronic devices, have properties somewhere between conductors and resistors. Most semiconductors are currently made of silicon or other rigid inorganic materials. Scientists have tried making flexible, degradable semiconductors using different approaches, but the products either didn’t break down completely or had reduced electrical performance when stretched. Zhenan Bao and colleagues wanted to see if they could solve these problems by combining a rubbery organic polymer with a semiconducting one. To make their new material, the researchers synthesized and mixed the two degradable polymers, which self-assembled into semiconducting nanofibers embedded in an elastic matrix. Thin films made of these fibres could be stretched to twice their normal length without cracking or compromising electrical performance. When placed in a weak acid, the new material degraded completely within 10 days, but it would likely take much longer in the human body, Bao says. The semiconductor was also non-toxic to human cells growing on the material in a petri dish. According to the researchers, this is the first example of a material that simultaneously possesses the three qualities of semiconductivity, intrinsic stretchability and full degradability.
http://www.sciencedaily.com/
