Gamma Irradiating Research Articles

Effects of γ radiation on rutting and fatigue performance of WPET asphalt mixtures

The generation of large amounts of waste polyethylene terephthalate (WPET) has caused serious environmental and health issues. This research aims to look into the potential reuse of WPET as a secondary material in highway construction and to assess the effect of gamma irradiation on the properties of WPET for use in asphalt concrete (AC) mixtures. Regular and gamma-irradiated WPET granules were used in AC mixes at optimal asphalt content levels. In different quantities, conventional granite aggregate was replaced with WPET granules (0, 10%, 20%, 30%, and 40% by volume). X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry were used to examine the mechanical and thermal properties of regular and gamma-irradiated WPET. Rutting tests were done at 60 ºC, and indirect tensile fatigue testing were performed at 20 ºC. Analytical investigations demonstrated that gamma irradiating WPET increased its mechanical and thermal qualities. Rutting experiments revealed that AC mixes containing WPET granules had lower rut depths than the control mix. The mixes containing standard WPET that had been modified with 20% WPET had the least rut depth. The substitution of granite aggregate in mixes containing gamma-irradiated WPET could be up to 40% while maintaining better rutting resistance. Furthermore, fatigue results revealed that WPET-modified AC mixes had considerably greater fatigue failure cycles at all stress levels than the control mix. Notably, AC combinations containing conventional WPET performed better than those including gamma-irradiated WPET. This study demonstrates how gamma irradiation improves WPET properties in AC mixes.Both regular and gamma-irradiated WPET-modified AC mixes outperformed the control mixture in terms of rutting and fatigue cracking resistance, adding to material sustainability in highway construction.

Utilizing of Spent Fuel Storage Pool in Gamma Irradiation Experiments

Abstract The objective of this study is suggesting a new method for gamma irradiating experiment using spent fuel elements (SFEs). An irradiation device was developed to contain the sample during the gamma irradiation process under water in spent fuel storage pool. The maximum burned fuel elements were used as a source of gamma rays with intensity and energy spectrum depend on the decay time from the reactor core withdrawal. A SFE configuration was introduced to verify an ideal condition of irradiating the sample with uniform gamma flux. The gamma dose rate inside the sample chamber was calculated using SCALE/MAVRIC code for the SFEs configuration source at decay times ranging between 0 and 5 years. A relationship was introduced to obtain the required accumulated dose depending on choosing the proper SFE configuration with the proper irradiation time.

Gamma irradiating chromatography columns enables bioburden-free integrated continuous biomanufacturing.

An important consideration for integrated continuous biomanufacturing is that the downstream chromatography steps integrated with the bioreactor should maintain a low bioburden state throughout the entire duration of the operation. One potential strategy to achieve this is to start bioburden-free and functionally close the chromatography system. While chromatography skids themselves can be rendered bioburden-free, limitations exist in applying these methods to chromatography columns. The small column sizes used in continuous multicolumn chromatography enable gamma irradiation of disposable columns to render them bioburden-free. However, this approach has not been widely implemented, likely because gamma irradiation can negatively impact resin performance. Here, several protective mobile-phase modifiers were screened and shown to help chromatography resins retain naïve-like performance. Gamma irradiated columns were then integrated into perfusion bioreactors for continuous capture. Successful integrated continuous capture downstream of perfusion bioreactors for greater than 40 days using protein A, custom affinity, and non-affinity capture resins for multiple biologic modalities is demonstrated in development and commercial settings. No indications of time-based performance decline or bioburden growth have been observed. This strategy enables bioburden-free integrated continuous biomanufacturing operations and could allow full process closure and decreased environmental control requirements for facilities; thus, permitting simultaneous multi-product operations in a ballroom arrangement.

Degradation of some organophosphorus pesticides in aqueous solution by gamma irradiation.

This study reviews the effect of different gamma radiation doses (1, 3, 5, 10 and 20 kGy) on the degradation of chlorfenvinphos, diazinon, dimethoate, and profenofos at different concentrations (0.5, 1.0, and 5 μg/mL) in aqueous solutions (deionized, tap, and groundwater). The role of initial concentration, measured total dissolved solids and pH on degradation was investigated. The degradation of the four tested organophosphates due to gamma irradiation was determined using LC-MS/MS. The radiolytic degradation products were studied using the scan mode of GC-MS/MS. The radiation chemical yield, dose constant, D0.5, and D0.9 were calculated to evaluate degradation efficiency for each compound. All pesticides are completely eliminated, despite water type, at low concentration levels of 0.5 and 1 μg/mL. At concentration level 5 μg/mL, gamma irradiation could completely remove pesticides concentration in de-ionized water, but the binding effect of total dissolved solids decreased degradation efficiency of some organophosphates such as diazinon. The D0.9 of 5 μg/mL concentration of chlorfenvinphos, diazinon, dimethoate, and profenofos in de-ionized water were 6.6, 8.7, 11.0, and 17.6 respectively. Also, Gamma irradiating of an agriculture wastewater sample resulted in the removal of carbaryl, carbosulfan, and diazinon at 6 kGy dose.

Evaluation of the thermoluminescence kinetic parameters of zinc‐borosilicate glass after gamma‐irradiation

AbstractUp until this moment, there was no detailed study concerning the kinetic parameters of zinc‐doped borosilicate glass thermoluminescent (TL) material. A significant TL peak was observed upon gamma irradiating the samples, at around 185°C. Evaluating activation energy (E), frequency factor (s), and order of kinetics (b) were conventionally obtained by peak shape (PS) method, repeated initial rise (RIR), and variable heating rate (VHR) methods. The obtained results indicated that the zinc‐doped borosilicate glass glow curve after gamma irradiation is legitimately a superposition of seven interfered glow peaks. Therefore, we cannot use computerized glow curve deconvolution (CGCD) method alone in determining the kinetic parameters in this case. Additive dose (AD), repeated initial raise (RIR), and variable heating rate (VHR) methods together with computerized deconvolution (CGCD) method by using the TolAnal software have been applied to determine the kinetic parameters of zinc‐borosilicate glass due to the existence of several nearby overlapped peaks. RIR method gives the value of ± 2.3% average variation, for the activation energies, compared with those obtained by GCDC. The obtained results clearly show the consequences reliability.

Concreto Polimérico Reforzado con Fibras de Luffa

A polymer concrete was prepared adding luffa fiber with the aim of improving compressive and flexural strength as well as elasticity. Polymer concrete specimens were prepared with unsaturated polyester resin with 30 % in volume being the remaining 70% siliceous sand and luffa fibers at several concentrations (0.3, 0.6 and 0.9 vol%). Specimens without fibers were evaluated and gamma irradiating. The evaluation of the mechanical resistance to compression and flexion of the specimens were done in a universal testing machine while elasticity modulus was determined with ultrasound equipment. After the mechanical tests the luffa fiber areas were analyzed using a scanning electronic microscopy. The results show that compressive strength, flexural strength and elasticity decrease their values for the specimens with fibers. The properties improved for the irradiated specimens.

감마선 조사선량에 따른 버찌(Fruit of Prunus serrulata L. var. spontanea Max. wils.) 에탄올 추출물의 항산화활성

본 연구는 폐자원으로 버려지는 버찌의 활용 증대방안 모색을 위한 기초자료 마련을 위해 버찌의 에탄올 추출물에 0～20 kGy 선량으로 감마선 조사를 실시하고, 이에 따른 항산화활성 변화를 측정하였다. 총 폴리페놀 함량 측정결과, 10 kGy 조사구에서 30.35 mg/g으로 가장 높은 값을 나타내었으나 감마선 조사에 따른 일정한 증가나 감소의 경향은 나타내지 않았다. DPPH radical 소거능 측정결과 10 kGy 조사구에서 327.52 ppm으로 가장 낮은 IC₅₀값을 나타내 가장 높은 활성을 나타내었으며 대체적으로 비조사구보다는 조사구에서 높은 활성을 나타내었다. 환원력 측정 결과, 2.5mg/mL 이하 농도에서 비조사구에 비해 조사구에서 높은 활성을 나타내었고 20 kGy 조사구에서 대체적으로 높은 환원력을 나타내었다. 아질산염 소거능을 측정한 결과 pH 4.2 이하의 pH에서 조사구 및 비조사구 모두 73～94% 이내의 높은 소거능을 나타내 pH 의존적인 아질산염 소거능을 보였으나 조사에 따른 활성 증가는 나타내지 않았다. FRAP value를 측정결과 3 kGy 조사구에서 0.38 mM로 가장 높은 활성을 나타내었다. 결론적으로 버찌 에탄올 추출물에 대한 감마선 조사는 일부 선량에서 추출물의 항산화 활성 증가를 나타내며, 사용목적에 따른 적정 선량의 감마선 조사는 생리 활성물질의 증가를 유도하여 산업적인 면에서 효율적으로 이용될 수 있을 것으로 사료된다.

Biodegradable Elastomeric Networks: Highly Efficient Cross-Linking of Poly(trimethylene carbonate) by Gamma Irradiation in the Presence of Pentaerythritol Triacrylate

Biodegradable elastomeric poly(trimethylene carbonate) (PTMC) networks were efficiently formed by gamma irradiating the linear polymer in the presence of pentaerythritol triacrylate (PETA). The properties of networks formed upon irradiation of PTMC films containing (0, 1, 5 wt %) PETA as a cross-linking aid were evaluated. The gel contents and network densities increased with increasing PETA contents, irradiation dose, and initial polymer molecular weights. At a dose of 25 kGy, networks with gel fractions up to 0.96 could be obtained. The networks were noncytotoxic, had elastic moduli below 10.7 MPa and high tensile strengths of up to 37.7 MPa. The incorporation of PETA also improved the resistance to creep and to tear propagation significantly, resulting in permanent set values that were as low as 0.9% strain and tear strengths up to 9.3 ± 2.0 N/mm. Furthermore, the enzymatic erosion rates of the networks could be decreased from 12.0 ± 2.9 to 3.0 ± 1.6 μm/day. These biodegradable elastomeric PTMC networks may be utilized in a broad range of medical applications.

A panel of radiation hybrids and YAC clones specific for human chromosome 5

We report the characterization, by reverse fluorescence in situ hybridization (FISH), of 59 hybrids retaining fragments of human chromosome 5. Most of these hybrids are radiation hybrids generated by gamma irradiating, at low dosage, a monochromosomal hybrid retaining chromosome 5 as its only human contribution. The partial chromosome paints generated from these hybrids will make powerful tools for cytogenetic investigations, especially on the cytogenetic evolution of primates, and examples are reported. The molecular characterization of these hybrids was refined using 74 sequence-tagged sites (STSs), which allowed the physical dissection of chromosome 5 into 71 distinct regions with an average length of 2.7 Mb. The panel, therefore, is also suitable for high-precision subregional mapping of new genes or sequences located on chromosome 5. As an additional resource for cytogenetic studies involving chromosome 5, we report the characterization, by FISH, of 73 YACs from CEPH. The vast majority of these YACs are recognized by at least one of the STSs used for hybrid characterization, thus enabling the integrated use of YACs and partial chromosome paints derived from the hybrids.

Effect of Gamma Irradiating Rye or Supplementing a Rye-Containing Layer Diet with Penicillin or Pectic Enzymes on Egg Production

The effects of gamma irradiating rye or supplementing a rye-containing layer diet with penicillin or the pectic enzyme (Irgazyme 100) were studied. Two experiments, one with 31-week-old and the other with 29-week-old White Leghorn hens were conducted. Each experimental diet was fed to four groups of hens in Experiment 1 and to five groups of hens in Experiment 2. Each group consisted of 15 individually caged hens.Substituting rye for corn in the control diet significantly depressed egg production. Addition of penicillin did not prevent the drop. Gamma irradiation of the rye at 6.2 Mrad significantly increased egg production to a level where it was not different from that of hens fed the corn control diet. Irradiation of rye did not affect egg weight significantly. Addition of the pectic enzyme significantly increased egg production of hens fed the rye diet for the first 3 weeks but by the end of week 8, the improvement by the pectic enzyme was not significant. Feed consumption was not affected by gamma irradiation or penicillin supplementation of rye.

Destruction of phytic acid in diet for germfree rats and mice during autoclaving or gamma irradiating.

Phytic acid contents in a practical diet for germfree mice and rats (L-485-Cr which is based on maize and soybean meal), raw soybeans, and soybean meal, on a dry matter basis, were about 1%, 1% and 1.6%, and phytate P/total P values were 43%, 52% and 62%, respectively.The phytate destruction effect of autoclaving and gamma irradiating the practical diet was observed.Phytate P destruction of diet L-485-Cr after autoclaving at 121°C for 30 minutes, which is a practical procedure for the sterilization of germfree animal diets, was 7%. In the experiment on one lot of the diet, phytate P detruction after autoclaving at 121°C for 30 minutes and 2 hours was 9% and 17%, respectively. Phytate P destruction of diet L-485-Cr after 5 Mrad gamma irradiation was 8%. It seems that the practical conditions for sterilization of the practical diet cause only moderate destruction of phytate.On the other hand, phytate P destruction in soybeans after 5 and 10 Mrad irradiation and in soybean meal after 5 Mrad irradiation were about 17%.