Structure and spectroscopy of methionyl-methionine for aquaculture

The amino acid L-methionine is an essential amino acid and is commonly used as a feed supplement in terrestrial animals. It is less suitable for marine organisms because it is readily excreted. It is also highly water soluble and this results in loss of the feed and eutrophication of the water. To address these problems, the dipeptide DL-methionyl-DL-methionine (trade name: AQUAVI Met-Met) has been developed as a dedicated methionine source for aquaculture. The commercial product is a mixture of a racemic crystal form of D-methionyl-D-methionine/L-methionyl-L-methionine and a racemic crystal form of D-methionyl-L-methionine/L-methionyl-D-methionine. In this work, we have computationally, structurally, spectroscopically and by electron microscopy characterised these materials. The microscopy and spectroscopy demonstrate that there is no interaction between the DD–LL and DL–LD racemates on any length scale from the macroscopic to the nanoscal

Phenoxy herbicides in Alberta rainfall: cause for concern?

Non-Peer ReviewedA survey for herbicides in air was conducted by analyzing rainfall at eight Lethbridge area locations. Rainfall samples were collected at weekly intervals from May 30 to August 17, 1998 and analyzed for 2,4-D, bromoxynil, dicamba, MCPA, diclofop, fenoxaprop, quinclorac, triallate and trifluralin using a MSD-GC method. With few exceptions, herbicides were detected at every sample date, at every location. 2,4-D was detected most frequently, and in the highest amounts, with bromoxynil and dicamba usually also present. The other herbicides were not detected. On June 12, 2,4-D was detected at two rural locations at 5.1 and 3.6 ppb compared with the Canadian Aquatic Life guideline of 4 ppb. Some high herbicide levels (2.0 and 4.3 ppb) also occurred in early July. Levels at the three city residences (maximum 1.0-1.6 ppb) were lower than at the rural locations. These herbicide detections results raise several concerns

Former Socialist Economies and the Undergraduate Curriculum

The authors report on the results of a survey of current undergraduate instruction on the socialist economic system and post-socialist economies. Based on responses from 80 colleges and universities, they evaluate how course offerings and content have changed in light of the momentous developments of the past decade. The evidence is then used to comment on trends and potential future developments in classes on comparative economic systems and transition economies. Although undergraduate offerings in these areas seem to have stabilised in the short term, there are good reasons to believe that the structure of these courses should soon be re-thought. Comparative Economic Studies, (2003) 45, 537–553. doi:10.1057/palgrave.ces.8100032