10K Pulse Tube Cooler
A 3-stage pulse tube cooler has been designed to operate at 10¶K. The staged cooler uses the same compressor and parallel staging configuration for the 1 st and 2 nd stages as previously employed for our delivered High Capacity Cryocooler (HCC). The 2 nd and 3 rd stages are in a serial configuration. The addition of the third stage extends the performance of this cooler to lower operating temperatures below 10¶K.
Experimental Investigation on Regenerator Materials of Stirling-type Pulse-tube Refrigerator Working at 20 K
Abstract This paper will introduce our recent experimental results of cryogenic regenerator materials employed in Stirling-type one-stage pulse-tube refrigerator for the use at liquid hydrogen temperature. Thermal diffusion coefficient, according to which we choose the suitable regenerator materials, will prove to be a useful reference. We will also discuss the impact of resistance of sphere regenerator materials on the performance of the refrigerator and the method to improve it. Take an overall consideration, suitable-size Er 3 Ni will be applied as the regenerator materials at the cold head and we achieve a remarkable 14.7 K no-load temperature.
Microbial flora of frozen tail meat from captive Nile crocodiles (Crocodylus niloticus).
Frozen tail meat samples from nine Nile crocodiles (Crocodylus niloticus) were evaluated for microbial numbers and types. Microbial analyses yielded a mean aerobic plate count (APC, 30 degrees C) of 4.86 log cfu/g, a mean coliform count (TC, 37 degrees C) of 3.77 log cfu/g and a mean faecal coliform count (FC, 44 degrees C) of 3.40 log cfu/g. Salmonella was isolated from three samples, and beta-haemolytic streptococci from two samples. Yersinia, Aeromonas, Staphylococcus aureus and Bacillus cereus were not isolated. Typical bacterial genera recovered included Flavobacterium, Pseudomonas, Acinetobacter, Enterobacter, Moraxella, Micrococcus, Staphylococcus and Streptococcus.