An internal standard method has been applied for the determination of lanthanum, antimony, scandium, chromium, iron and cobalt
in commercial cigarettes by neutron activation analysis using gold as an internal standard element. These trace elements were
separated from irradiated samples by APDC (ammonium pyrrolidine dithiocarbamate)/Zeph (tetradecyl dimethyl benzyl ammonium
chloride) coprecipitation, followed by direct gamma-counting of the separated precipitate using a Ge(Li) detector. Standard
reference tobacco 1R1 prepared by the University of Kentucky was also analyzed by this procedure for the above 6 elements,
the results of which were compared with literature values. Good results were obtained by the present method.
Many concerns over unsafe or unknown properties of multi-walled carbon nanotubes (MWNTs) have been raised. The thermal characteristics
regarding stability would represent potential hazards during the production or utilization stage and could be determined by
calorimetric tests for various thermokinetic parameters. Differential scanning calorimetry (DSC) was employed to evaluate
the thermokinetic parameters for MWNTs at various compositions.
Thermoanalytical curves showed that the average heat of decomposition (ΔHd) of the MWNTs samples in a manufacturing process was about 31,723 J g−1, by identifying them as an inherently hazardous material. In this study, significant thermal analysis appeared in the presence
of sulfuric acid (H2SO4). From the DSC experiments, the purification process of MWNTs could induce an unexpected reaction in the condition of batch
addition with reactants of H2SO4. The results can be applied for designing emergency relief system and emergency rescue strategies during a perturbed situation
A graphic method is proposed to determine all of the kinetic parameters in Wigner-Polanyi equation of desorption. A desorption rate curve from a single temperature-programmed desorption experiment is required by this method to determine the order of reaction (n), the activation energy (Ed) and the pre-exponential factor (v) of the equation. The proposed method has been applied to the oxygen desorption from PdO/Al2O3 samples prepared by impregnating γ-Al2O3 with H2PdCl4 solution used as examples. From the graphic method, the values ofn=2, andv=1.37±0.80×109 s−1 were successfully determined for the desorption. The value ofEd depended on the dispersion of palladium (D) on PdO/Al2O3 samples, and was expressed by the equation:Ed=175+174D kJ·mol−1. This graphic method is a direct and time-saving technique, on comparing with other methods suggested in the literature, for analysis of data from temperature-programmed desorption of simple desorption processes.
Organic peroxides (OPs) are very susceptible to thermal sources, chemical pollutants or even mechanical shock. Over the years,
they have caused many serious explosions. Cumene hydroperoxide (CHP) is widely employed to produce phenol and dicumyl peroxide
(DCPO) in the manufacturing process. Differential scanning calorimetry (DSC) and thermal activity monitor (TAM) were employed
to determine the potential thermal hazards and thermokinetic parameters (such as exothermic onset temperature (T0), maximum temperature (Tmax), and enthalpy (ΔH)) of CHP mixed with sodium hydroxide (NaOH) and sulfuric acid (H2SO4). High performance liquid chromatography (HPLC) was used to analyze the concentration vs. time of CHP.When CHP is mixed with NaOH, the T0 is induced earlier and reactions become more intricate than the pure CHP solution. CHP added to NaOH or H2SO4 is more dangerous than pure CHP alone. Depending on the operating conditions, NaOH and H2SO4 are the incompatible chemicals for CHP.
Organic peroxides have caused many serious explosions and fires that were promoted by thermal instability, chemical pollutants,
and even mechanical shock. Cumene hydroperoxide (CHP) has been employed in polymerization and for producing phenol and dicumyl
peroxide (DCPO). Differential scanning calorimetry (DSC) has been used to assess the thermal hazards associated with CHP contacting
sodium hydroxide (NaOH). Thermokinetic parameters, such as exothermic onset temperature (T0), peak temperature (Tmax), and enthalpy (ΔH) were obtained. Experimental data were obtained using DSC and curve fitting using thermal safety software (TSS) was employed
to obtain the kinetic parameters. Isothermal microcalorimetry (thermal activity monitor, TAM) was used to investigate the
thermal hazards associated with storing of CHP and CHP mixed with NaOH under isothermal conditions.
TAM showed that in the temperature range from 70 to 90°C an autocatalytic reaction occurs. This was apparent in the thermal
curves. Depending on the operating conditions, NaOH may be one of the chemicals or catalysts incompatible with CHP. When CHP
was mixed with NaOH, the T0 is lower and reactions become more complex than those associated with assessment of the decomposition of the pure peroxide.
The data by curve fitting indicated that the activation energy (Ea) for the induced decomposition is smaller than that for decomposition of CHP in the absence of hydroxide.
is one of the
species most commonly found in the wild field, which can cause severe infection and mortality in young sparrows. In this study, we selected
(Chung Hsing strain) as a pathogen to orally inoculate russet sparrows (
), spotted munia (
), canary (
), Java sparrows (
), chicken (
), ducks (
) and BALB/c mice. The results indicated that
infected only russet sparrows. Infected sparrows displayed lethargy, muscular weakness and fluffy feathers, followed by rapid death. Liver and spleen enlargement was seen in the infected birds. Schizonts were identified in thin smears from the venous blood, enlarged livers and spleens. Histopathological examination revealed schizonts and merozoites from the liver and spleen of infected russet sparrows, but not from other species experimentally inoculated with
in the present study.
Cumene hydroperoxide (CHP) and its derivatives have caused many serious explosions and fires in Taiwan as a consequence of
thermal instability, chemical contamination, and even mechanical shock. It has been employed in polymerization for producing
phenol and dicumyl peroxide (DCPO). Differential scanning calorimetry (DSC) was used to analyze the thermal hazard of CHP
in the presence of sodium hydroxide (NaOH), sulfuric acid (H2SO4), and sodium bisulfite (Na2SO3). Thermokinetic parameters for decomposition, such as exothermic onset temperature (T0), maximum temperature (Tmax), and enthalpy (ΔH), were obtained from the thermal curves. Isothermal microcalorimetry (thermal activity monitor, TAM) was employed to investigate
the thermal hazards during CHP storage and CHP mixed with NaOH, H2SO4, and Na2SO3 under isothermal conditions in a reactor or container. Tests by TAM indicated that from 70 to 90 °C an autocatalytic reaction
was apparent in the thermal curves. According to the results from the TAM test, high performance liquid chromatography (HPLC)
was, in turn, adopted to analyze the result of concentration versus time. By the Arrhenius equation, the activation energy
(Ea) and rate constant (k) were calculated. Depending on the process conditions, NaOH was one of the incompatible chemicals or catalysts for CHP. When
CHP is mixed with NaOH, the T0 is induced earlier and the reactions become more complex than for pure CHP, and the Ea is lower than for pure CHP.