A.
J. Patitsas
Abstract
The origin of the acoustic emissions from a bed of musical
grains, impacted by a pestle, is sought in a boundary layer
at the leading front of the pestle. The frequencies of the
shear modes of vibration in such a layer are compared with
the observed frequencies. It is assumed that such a layer is
the result of the fluidization of the grain asperities due
to the high stress level at the front end. Such a boundary
layer can also account for the emissions from plates of sand
sliding on a dune surface and from grains shaken in a jar.
Full Article
Synthesis and Degradation Studies of Nematic (N*) Liquid Crystals
Zohra N. Kayani, Saira Riaz, Shahzad Naseem
Abstract
Cholesteric Liquid Crystals (LCs) are synthesized and
characterized for their optical properties.
The optical properties of cholesteric LCs have been investigated with
varying applied field and
time. The electric field is applied in the range of 0V – 13V, whereas
time is varied between a few
seconds and 95 minutes. These cholesteric LCs are aged at room
temperature as well as at
higher temperatures up to 70oC. Degradation of these cholesteric LCs
under different conditions
is also reported in this paper. Multi-step purification process was
carried out and both the filtrate and residues are analyzed for phase
identification. XRD analysis confirms the presence and absence of the
main ingredients in the solution as well as in the residue.
Full Article
Abstract
Twelve fungal isolates recovered from oil-contaminated soils
were screened for crude oil
biodegradation activity in a shake-flask culture. Among the twelve
fungal isolates, only eight
showed potentials for biodegradation. Of these eight isolates, two of
them identified as
Aspergillus versicolor and Aspergillus niger which exhibited the fastest
onset and highest extent
of biodegradation were selected for further study on specific polycyclic
aromatic hydrocarbon
(PAH) biodegradation. Both isolates exhibited above 98% degradation
efficiency for polycyclic
aromatic hydrocarbon moieties when grown in a culture medium
incorporated with 1% crude oil
(hydrocarbon) and 0.1 %Tween 80 for 7 days.
Full Article
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