Microplastic and Organic Fibres in Feeding, Growth and Mortality of Gammarus pulex

Microplastic fibres (MPFs) are a major source of microplastic pollution, most are released during domestic washing of synthetic clothing. Organic microfibres (OMF) are also released into the environment by the same means, with cotton and wool being the most common in the UK. There is little empirical evidence to demonstrate that plastic fibres are more harmful than organic fibres if ingested by freshwater animals such as Gammarus pulex. Using our method of feeding Gammarus MPFs embedded in algal wafers, we compared the ingestion, feeding behaviour and growth of Gammarus exposed to 70 µm sheep wool, 20 µm cotton, 30 µm acrylic wool, and 50 µm or 100 µm human hair, and 30 µm cat hair at a concentration of 3% fibre by mass. Gammarus would not ingest wafers containing human hair, or sheep wool fibres. Given the choice between control wafers and those contaminated with MPF, cat hair or cotton, Gammarus spent less time feeding on MPF but there was no difference in the time spent feeding on OMFs compared to the control. Given a choice between contaminated wafers, Gammarus preferred the OMF to the MPF. There were no significant differences in growth or mortality among any of the treatments. These results conclude that MPFs are less likely to be ingested by Gammarus if alternative food is available and are not more harmful than OMFs.

Morphology Of Silicon Oxides On Silicon Carbide

The development of high power devices based on silicon carbide requires a more complete understanding of the oxide formation process and interface characteristics. By using an integrated UHV system, samples were cleaned and oxides deposited in situ. The approach of the oxide formation process was to form the initial insulator, a few angstroms thick, and then deposit an oxide. Various deposition techniques are used in the oxide growth process; both thermal and plasma enhanced chemical vapor deposition were employed with two different precursors (oxygen and nitrous oxide), and the results were compared with thermal oxidation. The morphology of each of the deposited oxides was compared to the bare substrate and the thermal oxide wafers. This study focuses on the morphology of the different deposition processes using AFM. Examination of the morphology of the initial insulator growth process and the oxide deposition process gives insight into the physical characteristics of the silicon dioxide deposited on silicon carbide. The RMS values of the initial insulator formation and the control wafers are 0.93 and 0.95 nm respectively. Meanwhile, the RMS values for PECVD (200–400°C) and thermal CVD (400–600°C for oxygen-silane and 800–1000°C for nitrous oxide-silane) range from 1.43 to 1.93 nm.

Ion Impiantation Doping of Siox with 31P and 69Ga

ABSTRACTImplantations of annealed SIMOX and Si wafers have been done using P and Ga to investigate the effect of excess oxygen and oxygen precipitates on amorphous layer regrowth and category II (end-of-range) dislocation loop elimination. Solid phase epitaxial regrowth of the amorphous silicon in both SIMOX and Si control wafers occurred at 550°C without the formation of category III defects and annealing at 900°C 16 hours resulted in complete removal of the category II defects. In an oxidizing ambient, the implanted SIMOX wafer again exhibited complete defect elimination whereas the Si control wafer showed growth and development of extrinsic stacking faults. It is speculated that the buried oxide may act as a sink for the Si. SIMS results indicate the dopant getters to the Si/SiO2 interfaces and that redistribution can be modelled reasonably well with SUPREME III.