Effect Of Irradiation Temperature Research Articles

Effect of UV irradiation, sample thickness and storage temperature on storability, bacterial activity and functional properties of liquid egg.

Effect of sample thickness, ultraviolet irradiation and storage temperature on bacterial activity, storability and functional properties (foamability and stability) of liquid egg were investigated. Eggs were contaminated with prepared Salmonella suspension 108/mL. Separated albumen and yolk samples were poured in three thicknesses (1, 2 and 3mm) and irradiated at 3, 5 10, 15min with ultraviolet radiation and were stored at 5, 15, 25, 37°C for up to 8days. Observations indicated that all ultraviolet irradiation times, reduced the total count of Salmonella bacteria in egg samples. Although, functional properties were improved, protein oxidation in both albumen and yolk increased. After the first 2days of storage, total counts of Salmonella and protein oxidation of eggs decreased solely in the 5°C treatment. It is concluded that irradiation treatment can be used to decrease bacterial contamination of liquid egg albeit not below the safe level for raw consumption. Furthermore, the best irradiation times to improve foam ability and stability were 10 and 5min, respectively.

Study of the dose response of the system ferrous ammonium sulfate–sucrose–xylenol orange in acid aqueous solution

Abstract An aqueous solution of ammonium ferrous sulfate–sucrose–xylenol orange in sulfuric acid (FSX) is proposed as a dosimetric system for the processes of gamma irradiation in a range between 0.3 and 6 Gy. This system is based on the indirect oxidation of ferrous ion by an organic compound (sucrose) to ferric ion and on the formation of a color complex of Fe 3+ in an acidic medium with xylenol orange (a dye). After gamma radiation, an observable change occurs in the color of the system. Irradiation was executed at three different temperatures (13 °C, 22 °C, and 40 °C). A spectrometric readout method at 585 nm was employed to evaluate the system׳s dose response. In all of the cases analyzed, the responses had a linear behavior, and a slight effect of irradiation temperature was observed. Post-irradiation response was also evaluated and showed the stability of the solutions 24 h after the irradiation. The results obtained suggest that FSX might be used as a dosimeter for low doses of gamma irradiation because it provides a stable signal, good reproducibility, and an accessible technique for analysis.

Effect of ultrasound irradiation on some freezing parameters of ultrasound-assisted immersion freezing of strawberries

In this study, the effect of ultrasound irradiation temperature and ultrasound intensity on the freezing and nucleation in strawberry samples was studied. The application of ultrasound irradiation at different temperatures was able to induce nucleation at lower degree of supercooling compared to the control samples. The achieved degree of supercooling in the ultrasound irradiated strawberries was linearly correlated to the ultrasound irradiation temperature. At the ultrasound irradiation temperature of −1.6 °C, the characteristic freezing time (CFT) was significantly shorter than that in the control sample (p < 0.05). The application of ultrasound at higher intensities was found to effectively shorten the CFT. The degree of supercooling in ultrasound irradiated samples was not linearly correlated to ultrasound intensity. In conclusion, the combination of ultrasound irradiation temperature and intensity can be effective in controlling nucleation and freezing processes of perishable fruits such as strawberry.

Evaluation of Physiological and Orgaleptic Properties of Mango cv. Kesar as Influenced by Ionizing Radiation and Storage Temperature

Radiation processing of fruits involves exposure to short wave energy to achieve a specific purpose to maintain the physiological changes and sensory quality of the product. The effect of gamma irradiation and storage temperature on physiological changes and organoleptic properties of mango fruit var. Kesar was studied. The fruits were exposed to gamma radiation at different doses i.e. 0.00kGy, 0.20kGy, 0.40kGy and 0.60kGy from the radio isotope 60Co and stored at different storage environments i.e. at ambient storage (27±2°Cwith 60-70% RH); at 9°C with 90% RH; at 12°C with 90% RH and control atmosphere storage ( at 12°C, O2 2%, CO2 3% and RH 90%). The fruits irradiated with 0.40kGy gamma rays and stored at 9°C storage temperature with 90% RH recorded maximum reduction in physiological loss in weight and reduced ripening. The minimum physiological loss in weight and ripening and highest marketability of fruits was recorded from fruits irradiated with 0.40kGy gamma rays and stored at 12°C storage temperature with 90 RH including maximum scores on skin colour, pulp colour, texture, taste and overall acceptability at the end of shelf life (41.43 days). DOI: http://dx.doi.org/10.3329/sja.v11i2.18403 SAARC J. Agri., 11(2): 69-80 (2013)

Degradation mechanisms of silicone rubber (SiR) by accelerated ageing for cables of nuclear power plant

The degradation behavior of SiR for the cable insulation by accelerated thermal and radiation ageing was studied and the degradation mechanism was proposed. The degradation was observed by the change of tensile properties, the distribution of crosslinking, and the change of weight. The chemical reaction under the both ageing in oxidation conditions was crosslinking and the oxidation mechanism was found to be the same between thermal and radiation ageing. The yield of crosslinking was proportional to the ageing time and also the dose. The effect of irradiation temperature on oxidation was accelerated with an increase of temperature above around 120°C, which might be due to the specific radiation chemical reactions. Therefore, the degradation by simultaneous ageing at higher temperatures above 155°C was much higher than that for sequential ageing, such as irradiation followed by thermal ageing or thermal ageing followed irradiation. At a high temperature, the degradation by thermal ageing under vacuum (without oxidation) was more progressed than that for the ageing in air (with oxidation). The reason was assumed to be the thermal decomposition of crosslinks between SiR molecules formed by the chemical crosslinking agent. The hardness (Shore hardness) reflected well the degradation of the SiR material for any ageing conditions.

Effect of microwave irradiation time and temperature on the spectroscopic and morphological properties of nanostructured poly(carbazole) synthesized within bentonite clay galleries

Polycarbazole chains form loops which extend into spirals within the clay galleries. These spirals reorganize into spheres, when extracted from clay galleries.

Rapid synthesis of iron 1,4-naphthalenedicarboxylate by microwave irradiation with enhanced gas sorption

A high quality crystalline porous coordination polymer (PCP), Fe(OH)(1,4-NDC)·2H2O (1,4-NDC = 1,4-naphthalenedicarboxylate), was successfully prepared using a rapid and efficient microwave irradiation method (hereafter termed M-PCP-Fe). It was noteworthy that the microwave irradiation method reduced the reaction time considerably to 1 min, while it took three days for the conventional hydrothermal method to prepare non-uniform crystal morphologies in a one-pot manner (hereafter termed H-PCP-Fe). The effects of microwave irradiation time, temperature and concentration were also investigated. According to the CO2 adsorption isotherms, it was found that M-PCP-Fe had a better performance on CO2 adsorption than H-PCP-Fe under the same conditions. This approach is expected to be widely used in large scale production of PCPs.

Intergranular Embrittlement of Nuclear Reactor Pressure Vessel Steels

Service life of VVER-type nuclear reactor is limited by decrease in brittle fracture resistance of reactor pressure vessel produced of low-alloy low-carbon steel under effect of irradiation and/or elevated temperatures. In this work fracture surfaces were studied by Auger-electron spectroscopy in order to estimate the contribution of intergranular embrittlement to the degradation of reactor pressure vessel steels under the influence of operating conditions. It was demonstrated that irradiation induced segregation leads to an increase of P content in grain boundaries that promotes intergranular brittle fracture on fracture surfaces. The similar effect but to a lesser degree was shown in the case of long-term temperature exposure. The grain boundary structure was examined and an effect of carbides located on the grain boundaries is supposed due to increased phosphorus segregation on carbide/matrix interface boundaries.

Effect of irradiation and storage temperature on quality parameters of Kesar mango (Mangifera indica L.)

An experiment was carried out to study the effect of irradiation and storage temperatures on quality parameters in Kesar mango fruits. The fruits were exposed to gamma radiation of different doses i.e. 0.00, 0.20, 0.40 and 0.60 kGy) from 60Co source and stored at various storage environment viz., ambient temperature 27 ± 2 °C and RH 60–70 %; temperature 9 °C and RH 90 %; 12 °C and RH 90 % and control atmospheric (CA) storage at 12 °C, O2 2 %, CO2 3 % and RH 90 %. The data indicated that highest total soluble solids, total and reducing sugars and ascorbic acid contend and minimum acidity were noted in 0.40 kGy gamma rays irradiated fruits stored at 12 °C compared to unirradiated fruits stored at ambient condition at ripening stage.

Neutron and X-ray diffraction analysis of the effect of irradiation dose and temperature on microstructure of irradiated HT-9 steel

Material harvested from several positions within a nuclear fuel duct (the ACO-3 duct) used in a 6-year irradiation of a fuel assembly in the Fast Flux Test Reactor Facility (FFTF) was examined using neutron and high-energy X-ray diffraction. Samples with a wide range of irradiation dose and irradiation temperature history, reaching doses of up to 147dpa and temperatures of up to 777K, were examined. The response of various microstructural characteristics such as the weight fraction of M23C6 carbides, the dislocation density and character, and the crystallographic texture were determined using whole profile analysis of the diffraction data and related to the macroscopic mechanical behavior. For instance, the dislocation density was observed to be intimately linked with observed flow strength of the irradiated materials, following the Taylor law. In general, at the high doses studied in this work, the irradiation temperature is the predominant controlling factor of the dislocation density and, thus, the flow strength of the irradiated material. The results, representing some of the first diffraction work done on samples exposed to such a high received dose, demonstrate how non-destructive and stand-off diffraction techniques can be used to characterize irradiation induced microstructure and at least estimate mechanical properties in irradiated materials without exposing workers to radiation hazards.

Effects of irradiation temperature and dose rate on the mechanical properties of self-ion implanted Fe and Fe–Cr alloys

Pure Fe and model Fe–Cr alloys containing 5, 10 and 14%Cr were irradiated with Fe+ ions at a maximum energy of 2MeV to the same dose of 0.6dpa at temperatures of 300°C, 400°C and 500°C, and at dose rates corresponding to 6×10−4dpa/s and 3×10−5dpa/s. All materials exhibited an increase in hardness after irradiation at 300°C. After irradiation at 400°C, hardening was observed only in Fe–Cr alloys, and not in the pure Fe. After irradiation at 500°C, no hardening was observed in any of the materials tested. For irradiations at both 300°C and 400°C, greater hardening was found in the Fe–Cr alloys irradiated at the lower dose rate. Transmission electron microscopy and atom probe tomography of Fe 5%Cr identified larger dislocation loop densities and sizes in the alloy irradiated with the high dose rate and Cr precipitation in the alloy irradiated with the low dose rate.

Modifications of SiC under high fluence Kr-ion irradiation at different temperatures

4MeV Kr-ions were irradiated into 6H–SiC single crystals with fluences from 1.0×1016 to 5.0×1016cm−2 at room temperature, 300°C and 500°C, respectively (5.0×1016cm−2 at 550°C). The irradiation-induced modifications were measured by Atomic Force Microscope (AFM), Raman Spectrometer and Nano-indentation measurements. It was observed that the surface of RT-irradiated samples became rough as a result of crystallizing to amorphous state. The result of Raman spectra indicates that different migration behaviors of Si and C interstitials at different temperatures could have an effect on the stoichiometry of irradiated samples. It was also observed that the hardness of irradiated samples is higher than that of un-irradiated ones at high temperatures, with increase at low fluence and then decrease at high fluence. Finally, the effects of irradiation temperature and ion fluence are discussed.

Temperature Dependent Photovoltaic (PV) Efficiency and Its Effect on PV Production in the World – A Review

Solar cell performance decreases with increasing temperature, fundamentally owing to increased internal carrier recombination rates, caused by increased carrier concentrations. The operating temperature plays a key role in the photovoltaic conversion process. Both the electrical efficiency and the power output of a photovoltaic (PV) module depend linearly on the operating temperature. The various correlations proposed in the literature represent simplified working equations which can be apply to PV modules or PV arrays mounted on free-standing frames, PV-Thermal collectors, and building integrated photovoltaic arrays, respectively. The electrical performance is primarily influenced by the material of PV used. Numerous correlations for cell temperature which have appeared in the literature involve basic environmental variables and numerical parameters which are material or system dependent. In this paper, a brief discussion is presented regarding the operating temperature of one-sun commercial grade silicon- based solar cells/modules and its effect upon the electrical performance of photovoltaic installations. Generally, the performance ratio decreases with latitude because of temperature. However, regions with high altitude have higher performance ratios due to low temperature, like, southern Andes, Himalaya region, and Antarctica. PV modules with less sensitivity to temperature are preferable for the high temperature regions and more responsive to temperature will be more effective in the low temperature regions. The geographical distribution of photovoltaic energy potential considering the effect of irradiation and ambient temperature on PV system performance is considered.

In-pile irradiation induced defects and the effect on thermal diffusivity of MgO

The effects of neutron irradiation temperature and dose on thermal diffusivity are investigated by comparing non-irradiated and in-pile irradiated MgO samples. MgO pellets were irradiated in-pile of the Advanced Test Reactor at Idaho National Laboratory. Samples were irradiated at 623 and 973K to fast neutron fluences of ∼1×1025 (1.5dpa) and ∼2×1025n/m2 (3dpa). Post irradiation examination included X-ray diffraction, scanning electron microscopy, laser flash thermal diffusivity, and transmission electron microscopy. Neutron irradiation of MgO causes a significant reduction in the thermal diffusivity (46%–72% at room temperature) due to irradiation-induced defects. The radiation induced thermophysical and structural evolution of MgO is reported.

Shape- and Morphology-Controlled Sustainable Synthesis of Cu, Co, and In Metal Organic Frameworks with High CO2Capture Capacity

We studied the effects of various surfactants on the shape and morphology of three metal organic frameworks (MOFs), i.e., Co-MOF, Cu-MOF, and In-MOF, which were synthesized under microwave irradiation. The as-synthesized materials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and nitrogen sorption. The effects of microwave irradiation time, temperature, and surfactant template were investigated. The synthetic parameters, including the type of surfactant template and the reaction temperature, played crucial roles in the size, shape, and morphology of the MOF microcrystals. We also evaluated these MOFs as sorbents for capturing CO2. Of the synthesized materials, Cu-MOF demonstrated the highest CO2 capture capacity, even at atmospheric pressure and ambient temperature.

Improved performance of nitro-blue tetrazolium polyvinyl butyral high dose film dosimeters

Improved performance in terms of dependence on humidity and irradiation temperature for radio-chromic film dosimeters with high dose range was achieved based on radiation-induced reduction of NBT2+. NBT-PVB film dosimeters containing different concentrations of NBT dye from 8 to 12 mM were prepared in a solution of 2-methoxyethanol. The dosimeters were irradiated with γ -ray from 60Co source at doses up to 100 kGy. UV/VIS spectrophotometer was used to investigate the optical density of un-irradiated and irradiated films in terms of absorbance at 525 nm. The absorbance increases with absorbed dose up to 100 kGy for NBT-PVB film dosimeters. The dose sensitivity of NBT-PVB film increases strongly with increase of concentrations of NBT dye. The effects of irradiation temperature, humidity, and the stability of the response of the films after irradiation were investigated. The stability of film dosimeters after irradiation was very high up to 60 days.

Superlinear dose response of thermoluminescence (TL) and optically stimulated luminescence (OSL) signals in luminescence materials: An analytical approach

The phenomenon of superlinear dose response of thermoluminescence (TL) and optically stimulated luminescence (OSL) signals has been reported for several important dosimetric materials. We develop new analytical equations for the filling of traps and centers during irradiation and for the read-out stage of annealed luminescence materials, within the context of a two-trap and two-center model. The equations are applicable for both TL and OSL signals in annealed dosimetric materials, and are derived under the assumptions of low irradiation doses and dominant strong retrapping (weak recombination) processes. For low doses all traps and centers display linear dose response, which leads to quadratic dose response of the integrated TL/OSL signals. A new analytical expression is presented for this well-known quadratic dose dependence, in terms of the kinetic parameters in the model. The effect of elevated irradiation temperature on the integrated TL/OSL signals is also considered, and analytical expressions are obtained for this situation as well. A new type of dose-rate effect is reported based on the modeling results, which is due to irradiation during elevated temperatures. The accuracy of the analytical expressions is verified by comparing with the results of numerical simulations.

Enhancement in sensitivity of nitro blue tetrazolium polyvinyl alcohol film dosimeters by sodium formate and Triton X-100

Nitro blue tetrazolium polyvinyl alcohol film dosimeters, NBT-PVA were prepared and evaluated based on radiation-induced reduction of NBT2+. NBT-PVA film dosimeters containing different concentrations of NBT dye from 1 to 5mM were prepared in a solution of ethanol. The dosimeters were irradiated with ϒ-ray from 60Co source at doses up to 50kGy. UV/vis spectrophotometer was used to investigate the optical density of un-irradiated and irradiated films in terms of absorbance at 529nm. The absorbance increases with absorbed dose up to 50kGy for NBT-PVA film dosimeters. The dose sensitivity of NBT-PVA film increases strongly with increase of concentrations of NBT dye. The effects of irradiation temperature, humidity, dose rate and the stability of the response of the films after irradiation were investigated. A considerable increase was observed in the dose response of NBT-PVA film by adding appropriate concentration of sodium formate and Triton X-100.

Facile one-step photochemical synthesis of water soluble CdTe(S) nanocrystals with high quantum yields

This paper describes a successful synthesis of water soluble CdTe(S) nanocrystals (NCs) with high quantum yields (QYs) via a mild photochemical route in one step with thioglycolic acid as the stabilizer and sulfur source. The precursor solution of mixed cadmium chloride, freshly prepared sodium hydrogen telluride and thioglycolic acid was subjected directly to UV irradiation using a 500 W high-pressure mercury lamp under the protection of N2. NCs with a small particle size (2.2 nm) and a high photoluminescence quantum yield (up to 80% at room temperature) were formed within 25 min. The NCs were characterized by UV-vis absorption and fluorescence spectroscopy, transmission electron microscopy, powder X-ray diffraction and energy-dispersive X-ray spectroscopy to evaluate their structure, size and composition. The photochemically prepared NCs were compared with CdTe NCs prepared by conventional hydrothermal synthesis and CdTe/CdS core/shell NCs obtained by post-preparative photochemical passivation. The effects of UV irradiation intensity, illumination time, temperature and concentration of Te2− on the optical properties of NCs were studied in detail.

A Study on a Solar Simulator for Dye Sensitized Solar Cells

Dye-sensitized solar cells (DSSC) are emerging low-cost, simple alternatives to conventional solar cells. While there has been considerable study on improving the efficiency of DSSCs, there has not been sufficient research on a photovoltaic power conditioning system adaptable to DSSCs or on a solar simulator for DSSCs. When DSSCs are commercialized in the near future, the DSSC modules must be connected to an adaptable power conditioning system in order to manage the energy produced and provide a suitable interface to the load. In the process of developing a power conditioning system, a solar simulator with the characteristics of DSSCs is essential to show the performance of the maximum power point tracking. In this paper, a virtual DSSC is designed and simulated in PSIM. Irradiation factors, temperature and shadow effects are considered in dynamic link library block in PSIM which is linked to the external C routine. A 100 W converter is built to show the performance of a DSSC as the solar simulator controlled by a digital signal processor.