Abstract: The paper presents a process to obtain glutathione-modified titanium oxide nanoparticles. The processes were carried out in a microwave radiation field. The influence of the molar ratio of glutathione to titanium oxide and the effect of the fold of NaOH vs. stoichiometric amount on the size of the formed TiO2 nanoparticles was determined. The physicochemical properties of the obtained products were evaluated using dynamic light scattering (DLS), transmission electron microscope- energy-dispersive X-ray spectroscopy (TEM-EDS), low-temperature nitrogen adsorption method (BET), X-Ray Diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) microscopy methods. The size of TiO2 nanoparticles was characterized from 30 nm to 336 nm. The release of titanium ions from the prepared products was evaluated. These studies were carried out using different media in which the powders were incubated for a specific time. These were: water, SBF and Ringer's solution. The release of titanium ions from modified products is weaker compared to unmodified titanium oxide nanoparticles. The reduced release of titanium ions may allow the use of such modified materials as substances in drug delivery systems.
Abstract: The new methods as accelerated steam distillation
assisted by microwave (ASDAM) is a combination of microwave
heating and steam distillation, performed at atmospheric pressure at
very short extraction time. Isolation and concentration of volatile
compounds are performed by a single stage. (ASDAM) has been
compared with (ASDAM) with cryogrinding of seeds (CG) and a
conventional technique, hydrodistillation assisted by microwave
(HDAM), hydro-distillation (HD) for the extraction of essential oil
from aromatic herb as caraway and cumin seeds. The essential oils
extracted by (ASDAM) for 1 min were quantitatively (yield) and
qualitatively (aromatic profile) no similar to those obtained by
ASDAM-CG (1 min) and HD (for 3 h). The accelerated microwave
extraction with cryogrinding inhibits numerous enzymatic reactions
as hydrolysis of oils.
Microwave radiations constitute the adequate mean for the
extraction operations from the yields and high content in major
component majority point view, and allow to minimise considerably
the energy consumption, but especially heating time too, which is one
of essential parameters of artifacts formation.
The ASDAM and ASDAM-CG are green techniques and yields an
essential oil with higher amounts of more valuable oxygenated
compounds comparable to the biosynthesis compounds, and allows
substantial savings of costs, in terms of time, energy and plant
material.
Abstract: Pretreatment is an essential step in the conversion of
lignocellulosic biomass to fermentable sugar that used for biobutanol
production. Among pretreatment processes, microwave is considered
to improve pretreatment efficiency due to its high heating efficiency,
easy operation, and easily to combine with chemical reaction. The
main objectives of this work are to investigate the feasibility of
microwave pretreatment to enhance enzymatic hydrolysis of
corncobs and to determine the optimal conditions using response
surface methodology. Corncobs were pretreated via two-stage
pretreatment in dilute sodium hydroxide (2 %) followed by dilute
sulfuric acid 1 %. Pretreated corncobs were subjected to enzymatic
hydrolysis to produce reducing sugar. Statistical experimental design
was used to optimize pretreatment parameters including temperature,
residence time and solid-to-liquid ratio to achieve the highest amount
of glucose. The results revealed that solid-to-liquid ratio and
temperature had a significant effect on the amount of glucose.
Abstract: We derive simple sets of equations to describe the microwave response of a thin film of magnetized hydrogen plasma in the presence of carbon nanotubes, which were grown by ironcatalyzed high-pressure disproportionation (HiPco). By considering the interference effects due to multiple reflections between thin plasma film interfaces, we present the effects of the continuously changing external magnetic field and plasma parameters on the reflected power, absorbed power, and transmitted power in the system. The simulation results show that the interference effects play an important role in the reflectance, transmittance and absorptance of microwave radiation at the magnetized plasma slab. As a consequence, the interference effects lead to a sinusoidal variation of the reflected intensity and can greatly reduce the amount of reflection power, but the absorption power increases.
Abstract: Soils are normally dried in either a convection oven or stove. Laboratory moisture content testing indicated that the typical drying durations for a convection oven were, 24 hours. The purpose of this study was to determine the accuracy and soil drying duration of both, moisture content and liquid limit using microwave radiation. The soils were tested with both, convection and microwave ovens. The convection oven was considered to produce the true values for both, natural moisture content and liquid limit of soils; it was, therefore, used as a basis for comparison for the results of the microwave ovens. The samples used in this study were obtained from different projects of Consulting Engineering Bureau of College of Engineering of Sulaimani University. These samples were collected from different locations and at the different depths and consist mostly of brown and light brown clay and silty clay. A total of 102 samples were prepared. 26 of them were tested for natural moisture determination, while the other 76 were used for liquid limits determination
Abstract: Variations in the growth rate constant of the Listeria
monocytogenes bacterial species were determined at 37°C in
irradiated environments and compared to the situation of a nonirradiated
environment. The bacteria cells, contained in a suspension
made of a nutrient solution of Brain Heart Infusion, were made to
grow at different frequency (2.30e2.60 GHz) and power (0e400
mW) values, in a plug flow reactor positioned in the irradiated
environment. Then the reacting suspension was made to pass into a
cylindrical cuvette where its optical density was read every 2.5
minutes at a wavelength of 600 nm. The obtained experimental data
of optical density vs. time allowed the bacterial growth rate constant
to be derived; this was found to be slightly influenced by microwave
power, but not by microwave frequency; in particular, a minimum
value was found for powers in the 50e150 mW field.