RESUMEN
Described here is the current status of the upgraded in situ size-exclusion chromatography (SEC) system implemented with the D22 small-angle neutron scattering (SANS) instrument at the Institut Laue-Langevin. Since its initial proof of principle in 2016, this SEC-SANS arrangement has been continuously requested by the user community, leading to the design of an upgraded version. A detailed description of the setup and its control is provided, and a few examples of protein structural investigations are presented, which will highlight the various possibilities and limitations of the setup to optimize experimental success.
RESUMEN
Exploiting small-angle X-ray and neutron scattering (SAXS/SANS) on the same sample volume at the same time provides complementary nanoscale structural information in two different contrast situations. Unlike an independent experimental approach, the truly combined SAXS/SANS experimental approach ensures the exactness of the probed samples, particularly for in situ studies. Here, an advanced portable SAXS system that is dimensionally suitable for installation in the D22 zone of ILL is introduced. The SAXS apparatus is based on a Rigaku switchable copper/molybdenum microfocus rotating-anode X-ray generator and a DECTRIS detector with a changeable sample-to-detector distance of up to 1.6â m in a vacuum chamber. A case study is presented to demonstrate the uniqueness of the newly established method. Temporal structural rearrangements of both the organic stabilizing agent and organically capped gold colloidal particles during gold nanoparticle growth are simultaneously probed, enabling the immediate acquisition of correlated structural information. The new nano-analytical method will open the way for real-time investigations of a wide range of innovative nanomaterials and will enable comprehensive in situ studies on biological systems. The potential development of a fully automated SAXS/SANS system with a common control environment and additional sample environments, permitting a continual and efficient operation of the system by ILL users, is also introduced.
RESUMEN
The first implementation and use of an in situ size exclusion chromatography (SEC) system on a small-angle neutron scattering instrument (SANS) is described. The possibility of deploying such a system for biological solution scattering at the Institut Laue-Langevin (ILL) has arisen from the fact that current day SANS instruments at ILL now allow datasets to be acquired using small sample volumes with exposure times that are often shorter than a minute. This capability is of particular importance for the study of unstable biological macromolecules where aggregation or denaturation issues are a major problem. The first use of SEC-SANS on ILL's instrument D22 is described for a variety of proteins including one particularly aggregation-prone system.
RESUMEN
Aquaculture is one of the fastest growing food-producing sectors, supplying approximately 40% of the world's fish food. Besides such benefit to the society, the industry does have its problems. There are occupational hazards and safety concerns in the aquaculture industry. Some practices have caused environmental degradation. Public perception to farmed fish is that they are "cleaner" than comparable wild fish. However, some farmed fish have much higher body burden of natural and man-made toxic substances, e.g. antibiotics, pesticides, and persistent organic pollutants, than wild fish. These contaminants in fish can pose health concerns to unsuspecting consumers, in particular pregnant or nursing women. Regulations and international oversight for the aquaculture industry are extremely complex, with several agencies regulating aquaculture practices, including site selection, pollution control, water quality, feed supply, and food safety. Since the toxicological, environmental, and health concerns of aquaculture have not been adequately reviewed recently, we are providing an updated review of the topic. Specifically, concerns and recommendations for improving the aquaculture industry, and for protection of the environment and the consumers will be concisely presented.