Abstract: The major source of allergy in home is the house dust
mite (Dematophagoides farina, Dermatophagoides pteronyssinus)
causing allergic symptom include atopic dermatitis, asthma, perennial
rhinitis and even infant death syndrome.
Control of this mite species is dependent on the use of chemical
methods such as fumigation treatments with methylene bromide,
spraying with organophosphates such as pirimiphos-methyl, or
treatments with repellents such as DEET and benzyl benzoate.
Although effective, their repeated use for decades has sometimes
resulted in development of resistance and fostered environmental and
human health concerns. Both decomposing animal parts and the
protein that surrounds mite fecal pellets cause mite allergy. So it is
more effective to repel than to kill them because allergen is not living
house dust mite but dead body or fecal particles of house dust mite.
It is important to find out natural repellent material against house
dust mite to control them and reduce the allergic reactions. Plants may
be an alternative source for dust mite control because they contain a
range of bioactive chemicals.
The research objectives of this paper were to verify the acaricidal
and repellent effects of cinnamon essential oil and to find out it-s most
effective concentrations. We could find that cinnamon bark essential
oil was very effective material to control the house dust mite.
Furthermore, it could reduce chemical resistance and danger for
Abstract: Acute toxicity of nano SiO2, ZnO, MCM-41 (Meso
pore silica), Cu, Multi Wall Carbon Nano Tube (MWCNT), Single
Wall Carbon Nano Tube (SWCNT) , Fe (Coated) to bacteria Vibrio
fischeri using a homemade luminometer , was evaluated. The values
of the nominal effective concentrations (EC), causing 20% and 50%
inhibition of biouminescence, using two mathematical models at two
times of 5 and 30 minutes were calculated. Luminometer was
designed with Photomultiplier (PMT) detector. Luminol
chemiluminescence reaction was carried out for the calibration graph.
In the linear calibration range, the correlation coefficients and
coefficient of Variation (CV) were 0.988 and 3.21% respectively
which demonstrate the accuracy and reproducibility of the instrument
that are suitable. The important part of this research depends on how
to optimize the best condition for maximum bioluminescence. The
culture of Vibrio fischeri with optimal conditions in liquid media,
were stirring at 120 rpm at a temperature of 150C to 180C and were
incubated for 24 to 72 hours while solid medium was held at 180C
and for 48 hours. Suspension of nanoparticles ZnO, after 30 min
contact time to bacteria Vibrio fischeri, showed the highest toxicity
while SiO2 nanoparticles showed the lowest toxicity. After 5 min
exposure time, the toxicity of ZnO was the strongest and MCM-41
was the weakest toxicant component.
Abstract: A comparative evaluation of acute toxicity of
synthesized nano silvers using two different procedures (biological
and chemical reduction methods) and silver ions on bacteria
Vibrio fischeri was investigated. The bacterial light inhibition test as
a toxicological endpoint was used by applying of a homemade
luminometer. To compare the toxicity effects as a quantitative
parameter, a nominal effective concentrations (EC) of chemicals and
a susceptibility constant (Z-value) of bacteria, after 5 min and 30 min
exposure times, were calculated. After 5 and 30 min contact times,
the EC50 values of two silver nanoparticles and the EC20 values were
about similar. It demonstrates that toxicity of silvers was independent
of their procedure. The EC values of nanoparticles were larger than
those of the silver ions. The susceptibilities(Z- Values) of V.fischeri
(L/mg) to the silver ions were greater than those of the nano silvers.
According to the EC and Z values, the toxicity of silvers decreased in
the following order: Silver ions >> silver nanoparticles from
chemical reduction method ~ silver nanoparticles from biological