Dose Of Gamma-ray Irradiation Research Articles

Enhanced UV photodetection in SnO2 microwire arrays (MWAs) thin films by γ-ray irradiation

In this study, the gamma ray irradiation-induced photoelectric responses of SnO2 microwire arrays (MWAs) UV photodetectors were investigated and compared with the unirradiated state. The corresponding surface morphology, crystal structure, and XPS spectrum were analyzed. Results indicated that low doses (≤500krad) of gamma ray irradiation led to enhanced photocurrent and responsivity, whereas high doses resulted in significant degradation of the photoelectric response. At a radiation dose of 300krad, a photocurrent of 264 μA and a responsivity of 1.83 A/W were realized under 365 nm UV light illumination at a bias voltage of 5 V. These values represent an increase of 34.6 % and 44.1 %, respectively, compared with the unirradiated sample. Surprisingly, the fabricated SnO2 MWAs UV photodetectors demonstrated resilience to gamma ray irradiation doses up to 500krad, which is equivalent to the radiation dose accumulated by satellites in low-Earth orbit over 20 years. Our findings suggested that the fabricated SnO2 microwire arrays (MWAs) UV detector has the potential to be used for long-term space missions.

Effects of chemical treatment and gamma-ray irradiation on the structure-properties of sunn hemp and okra hessian cloth reinforced high-density polyethylene composites: A comparative study

Okra hessian cloth and Sunn hemp hessian cloth were prepared and treated with 5, 10, and 15 wt% alkali solutions for 1 h. The optimized concentration of alkali is 10 wt%. The untreated and treated hessian cloths reinforced high-density polyethylene (HDPE) composites were then prepared using the compression molding method. Alkali-treated, and 55 wt% fiber contents reinforced composites showed improved mechanical properties among 40, 45, 50, 55, 60, and 65 wt% fiber contents composites. 55 wt% fiber contents reinforced composites were then irradiated under gamma-ray at doses 2.5–7.5 kGy at the rate of 6 kGy/h. According to the X-ray diffraction analysis results, only alkali-treated Okra reinforced, and Sunn hemp-reinforced HDPE composites had higher crystallinity values than untreated and irradiated composites. Surface micrographs showed that the Okra-HDPE and Sunn hemp-HDPE had better matrix and fiber attachment. Cross-linking between the two varieties of fibers and matrix was seen using Fourier-transform infrared (FTIR) spectroscopy. Both irradiated composites exhibited greater hydrophobicity in their water intake characteristics compared to untreated and alkali-treated composites. The tensile strength ( TS) value of Sunn hemp composite for 5 kGy gamma-ray irradiation dose is 68 MPa, which is 14% and 42% higher than that of treated and untreated composites, respectively. For comparison, the TS value for 5 kGy dose irradiated Okra composite is 66 MPa, which is 17% and 44% higher than that of treated and untreated composites, respectively. Young’s modulus ( Y) values of irradiated Okra composite and irradiated Sunn hemp composite showed higher values than that of other composites. Both irradiated composites have better thermal and structural characteristics than untreated and alkali-treated composites.

Diversity induction with gamma-ray irradiation on Phalaenopsis amboinensis var. Common natural orchid generation M1V0

Phalaenopsis is a popular genus in the Orchidaceae family. Phalaenopsis amboinensis orchid is an endangered natural orchid, so it needs to be preserved. Conservation of natural orchid Phalaenopsis amboinensis var. Common way is by increasing genetic diversity. This research aims to determine the characteristics and morphological diversity of Phalaenopsis amboinensis natural orchid irradiated gamma-ray results and without gamma-ray irradiation; this research was conducted in two places: the implementation of gamma-ray irradiation at the PAIR-BATAN Laboratory and in Matesih, Karanganyar with an average height of 450 m above sea level. The research was conducted from December 2022 to May 2023. The study used a simple design of one factor, the doses of gamma-ray irradiation with 5 levels: 0 Gy (R0), 7.5 Gy (R1), 15 Gy (R2), 22.5 Gy (R3), 30 Gy (R4). Each treatment contained five accessions. So, there are 25 experimental units. Observational data were analyzed descriptively by comparing observational data from Phalaenopsis amboinensis var. Common Generation M1V0 orchids irradiated with control plants. The results showed diversity in the morphology of the Phalaenopsis amboinensis var. Common orchid Generation M1V0 results from gamma-ray irradiation based on qualitative morphology with phenotypic observations, showing two orchid leaf shapes: oblanceolate and elliptic. There are accessions with fasciated root conditions.

Growth performance, yield, and proline content of two local cultivars of black rice irradiated by gamma rays for drought resistance

One of the critical effects of climate change on the agricultural environment is drought stress. This study aimed to determine the growth, yield performance, and proline content of black rice local cultivars Bantul, Boyolali mutant M2 at various doses of gamma rays and the proline content of mutant M3 during drought stress. The experiment used a Completely Randomized Design (CRD) with the factor dose of gamma-ray irradiation (0 Gy, 100 Gy, 200 Gy, and 300 Gy), applied in both paddy fields and polybags to observe and compare the growth, yield, and proline content of black rice plants with the control treatment (0 Gy). Laboratory test results showed that Boyolali and Bantul cultivars irradiated at 100 Gy and 200 Gy, had the highest proline content, which increased under drought stress conditions in both cultivars. At 100 Gy, the average plant height and the number of productive tillers of black rice of Boyolali and Bantul cultivars were the highest, and the diversity of the two local cultivars at this dose was higher than at other irradiation doses. Applying 100 Gy and 200 Gy gamma-ray irradiation doses on the Boyolali cultivar significantly affected the panicle length character and the number of seeds per panicle. For the Bantul cultivar, panicle length and the number of seeds per panicle at an irradiation dose of 200 Gy showed significantly different results. The conclusion is that a reduced amount of gamma-ray irradiation can enhance the growth, yield, and proline content of M2 black rice

Effects of post-processing curing parameters and gamma irradiation on the mechanical properties of medical graded vat photopolymerization parts

Purpose This paper aims to investigate the influence of post-curing temperature, post-curing time and gamma ray irradiation dose upon the tensile and compressive mechanical properties of the medical graded vat photopolymerization parts. Design/methodology/approach Medical graded vat photopolymerization specimens, made from photopolymer resin, were fabricated using bottom-up vat photopolymerization machine. Tensile and compressive tests were conducted to assess the mechanical properties. The specimens were categorized into uncured and post-curing groups. Temperature post-processing and/or gamma irradiation exposure were for post-curing specimens. The post-curing parameters considered included temperature levels of 50°C, 60°C and 70°C, with 1, 2, 3 and 4 h periods. For the gamma irradiation, the exposure doses were 25, 50, 75 and 100 kGy. Findings Post-curing improved the mechanical properties of medical graded vat photopolymerization parts for both tensile and compressive specimens. Post-curing temperature greater than 50°C or a prolonged post-curing period of more than 1 h made insignificant changes or deterioration in mechanical properties. The optimal post-curing condition was therefore a 50°C post-curing temperature with 1 h post-curing time. Exposure to gamma ray improved the compressive mechanical properties, but deteriorated tensile mechanical properties. Higher gamma irradiation doses could decrease the mechanical properties and also make the part more brittle, especially for doses more than 25 kGy. Originality/value The obtained results would be beneficial to the medical device manufacturer who fabricated the invasive temporary contact personalized surgical instruments by vat photopolymerization technique. In addition, it also raised awareness in excessive gamma sterilization in the medical graded vat photopolymerization parts.

Gamma-Ray-Induced Amino Acid Formation during Aqueous Alteration in Small Bodies: The Effects of Compositions of Starting Solutions.

Organic compounds, such as amino acids, are essential for the origin of life, and they may have been delivered to the prebiotic Earth from extra-terrestrial sources, such as carbonaceous chondrites. In the parent bodies of carbonaceous chondrites, the radioactive decays of short-lived radionuclides, such as 26Al, cause the melting of ice, and aqueous alteration occurs in the early stages of solar system formation. Many experimental studies have shown that complex organic matter, including amino acids and high-molecular-weight organic compounds, is produced by such hydrothermal processes. On the other hand, radiation, particularly gamma rays from radionuclides, can contribute to the formation of amino acids from simple molecules such as formaldehyde and ammonia. In this study, we investigated the details of gamma-ray-induced amino acid formation, focusing on the effects of different starting materials on aqueous solutions of formaldehyde, ammonia, methanol, and glycolaldehyde with various compositions, as well as hexamethylenetetramine. Alanine and glycine were the most abundantly formed amino acids after acid hydrolysis of gamma-ray-irradiated products. Amino acid formation increased with increasing gamma-ray irradiation doses. Lower amounts of ammonia relative to formaldehyde produced more amino acids. Glycolaldehyde significantly increased amino acid yields. Our results indicated that glycolaldehyde formation from formaldehyde enhanced by gamma rays is key for the subsequent production of amino acids.

In vitro mutagenesis on patchouli (Pogostemon cablin Benth.) with gamma-ray irradiation on leaf explants

Abstract. Normasari R, Arumingtyas EL, Retnowati R, Widoretno W. 2023. In vitro mutagenesis on patchouli (Pogostemon cablin Benth.) with gamma-ray irradiation on leaf explants. Biodiversitas 24: 6407-6414. Patchouli oil production in Indonesia has yet to meet international market demand, one of which is the quality of the patchouli superior seeds. Patchouli is propagated vegetatively through cuttings, causing limited variability and decreasing plant quality. In vitro mutagenesis with gamma-ray irradiation can increase plant genetic variability and produce superior patchouli plants. This study aimed to produce patchouli variants through in vitro mutagenesis by gamma-ray irradiation on patchouli leaf explants. To accomplish the research objectives mentioned above, the research stages included in vitro mutagenesis through gamma-ray irradiation, shoot regeneration, plantlet growth, and molecular analysis using SSR (Simple Sequence Repeat). Gamma-ray irradiation inhibited the growth of explants and shoot formation but could increase plantlet growth ability at low doses of 15-30 Gy. The dose of gamma-ray irradiation that caused the death of explants in fifty percent of the tested population (LD50) was 69 Gy. Molecular analysis of SSR on 50 plants regenerated from gamma-irradiated explants revealed monomorphic and polymorphic fragments compared to non-irradiated and donor plants. Primers Pca1 and Pca2 showed the highest percentage of polymorphic, with 77.3 and 50%, respectively. Gamma irradiation during in vitro culture is an alternate method for increasing genetic variety in patchouli breeding.

Improvement of intergranular corrosion resistance of SS 304L by grain refinement followed by gamma-ray irradiation treatment for the application in the back end of the nuclear fuel cycle

The severe plastic deformation (SPD) technique has been widely used for grain refinement to produce bulk ultra fine-grained (UFG) microstructure. In this study, an improved corrosion-resistant material of type 304L stainless steel (SS) has been designed, from the coarse-grain (CG) microstructure to the UFG microstructure using the SPD technique through cryo-rolling at liquid nitrogen (at 77K) temperature followed by gamma-ray irradiation treatment. In comparison to the effect of gamma-ray on both CG and UFG microstructure, both specimens were irradiated with an equal amount of doses. Gamma (γ) ray irradiation (dose rate: 2.83 kGy/h) affected the corrosion resistance of AISI type 304L stainless steel (in both CG and UFG) in concentrated nitric acid (65 wt%) medium. The correlation of irradiation effects on the microstructure and nitric acid corrosion behaviors has been discussed, which is important for designing materials for application in nuclear-spent fuel reprocessing plants.

PENDUGAAN PARAMETER GENETIK TANAMAN CABAI KATOKKON (CAPSICUM CHINENSE JACQ) DENGAN IRADIASI SINAR GAMMA

Katokkon chili is local horticultural commodity originating from Toraja and is often called katokkon pepper. This chili has good adaptation with a fairly high yield. The people of Toraja and the surrounding area really like this type of chili because it has one of the advantages of a production period that is not too long, around 3-4 months after transplanting. The purpose of this study was to determine the effect of giving a dose of gamma ray irradiation on the genetic parameters of katokkon chili plants. The use of this research as a basis for developing and improving genetics in breeding katokkon chili plants eith a dose of gamma irradiation. The implementation of the research was carried out at BTP. Tamalanrea, Tamalanrea District, Makassar City, South Sulawesi and the Integrated Farming System Education Garden, on Jl. Raya Poros Sappaya, Bontoramba Village, Pallangga District, Gowa Regency, from March to July 2023. The plants came from the control treatment (D0) and 200 Gray (D1) consisted of 3 replicates for each treatment and each experiment consisted of 15 plants, so that the total number of plants in this study was 90 plants. The research was carried out in the form of a randomized block design (RBD) with a dose of gamma irradiation as the main factor. The results showed that gamma irradiation at doses of 200 Gray could have a genetic effect compared to D0 on flowering age, number of fruit planted, fruit diameter, fruit weight, fruit stalk diameter, fruit length and fruit flesh thickness.

A single targeted gamma-ray irradiation induced an acute modulation of immune cells and related cytokines in EMT6 mouse-bearing tumour model.

A complicated interplay between radiation doses, tumour microenvironment (TME), and host immune system is linked to the active participation of immune response. The effects of single targeted 2 Gy and 8 Gy gamma-ray irradiations on the immune cell population (lymphocytes, B-cells, T-cells, neutrophils, eosinophils, and macrophages) in EMT6 mouse-bearing tumour models was investigated. The effects of both irradiation doses in early (96 hours) and acute phase (5 to 11 days) post-irradiation on immune parameters were monitored in blood circulation and TME using flow cytometry. Simultaneously, selected cytokines related to immune cells within the TME were measured using multiplex ELISA. A temporary reduction in systemic total white blood count (TWBC) resulted from an early phase (96 hours) of gamma-ray irradiation at 2 Gy and 8 Gy compared to sham control group. No difference was obtained in the acute phase. Neutrophils dominated among other immune cells in TME in sham control group. Eosinophils in TME was significantly increased after 8 Gy treatment in acute phase compared to sham control (p< 0.005). Furthermore, the increment of tumour necrosis (TNF)-α, eotaxin and interleukin (IL)-7 (p< 0.05) in both treatment groups and phases were associated with anti-tumour activities within TME by gamma-ray irradiation. The temporary changes in immune cell populations within systemic circulation and TME induced by different doses of gamma-ray irradiation correlated with suppression of several pro-tumorigenic cytokines in mouse-bearing EMT6 tumour models.

Retinal regeneration after injury induced by gamma-ray irradiation during early embryogenesis in medaka, Oryzias latipes

Purpose Zebrafish, a small fish model, exhibits a multipotent ability for retinal regeneration after damage throughout its lifetime. Compared with zebrafish, birds and mammals exhibit such a regenerative capacity only during the embryonic period, and this capacity decreases with age. In medaka, another small fish model that has also been used extensively in biological research, the retina’s inner nuclear layer (INL) failed to regenerate after injury in the hatchling at eight days postfertilization (dpf). We characterized the regenerative process of the embryonic retina when the retinal injury occurred during the early embryonic period in medaka. Methods We employed a 10 Gy dose of gamma-ray irradiation to initiate retinal injury in medaka embryos at 3 dpf and performed histopathological analyses up to 21 dpf. Results One day after irradiation, numerous apoptotic neurons were observed in the INL; however, these neurons were rarely observed in the ciliary marginal zone and the photoreceptor layer. Numerous pyknotic cells were clustered in the irradiated retina until two days after irradiation. These disappeared four days after irradiation, but the abnormal bridging structures between the INL and ganglion cell layer (GCL) were present until 11 days after irradiation, and the neural layers were completely regenerated 18 days after irradiation. After gamma-ray irradiation, the spindle-like Müller glial cells in the INL became rounder but did not lose their ability to express SOX2. Conclusions Irradiated retina at 3 dpf of medaka embryos could be completely regenerated at 18 days after irradiation (21 dpf), although the abnormal layer structures bridging the INL and GCL were transiently formed in the retinas of all the irradiated embryos. Four days after irradiation, embryonic medaka Müller glia were reduced in number but maintained SOX2 expression as in nonirradiated embryos. This finding contrasts with previous reports that 8 dpf medaka larvae could not fully regenerate damaged retinas because of loss of SOX2 expression.

Determination of the Sterilization Dose of Gamma-Ray Irradiation for Polyvinyl Alcohol-Collagen-Chitosan Composite Membrane as a Material for Periodontal Regenerative Surgery.

Membrane sterility is very necessary considering its function as an implant material. Therefore, this research aims to determine the dose of gamma-ray irradiation for the sterilization of polyvinyl alcohol (PVA)-collagen-chitosan composite membranes used as regenerative surgery materials. A total of 100 pieces of the composite membranes were prepared in a size of 2.0 × 1.5 cm by mixing 7.5% PVA, 3% collagen, and 2% chitosan using the film casting method in three batches. Furthermore, the bioburden test was performed to determine the initial microbial count in the sample by following ISO 11737-1. The results were used to ascertain the dose of gamma-ray irradiation on the sample according to ISO 11137-2. The dose verification test was then performed at the sterility assurance level 10-6. The average result of the bioburden test from three batches was 6.6 colony forming unit; hence, the verification dose was 4.8 kGy. In the verification dose test, since there was only one contaminated sample, the sterility dose test was continued. The sterile gamma-ray irradiation dose for PVA-collagen-chitosan composite membrane was 17.1 kGy.

Synthesis and characterization of gamma irradiated polyvinyl chloride/graphite carbon nitride nanocomposite films for electronic applications

This study introduces the synthesis of graphite-carbon nitrite (g-C3N4) using thermal treatment of urea. The prepared powder is treated to generate nanoparticles. The structure and grain size of the g-C3N4 have been obtained via X-ray diffraction (XRD) technique and transmission electron microscope. The graphite-carbon nitride on Polyvinyl Chloride (PVC/g-C3N4) nanocomposite films were produced by mixing different concentrations (0, 3, 5, 7, 10 and 20 wt%) of nanoparticles with Polyvinyl Chloride (PVC) solutions. The structure and elemental composition of the prepared nanocomposites films PVC/g-C3N4 were studied by using XRD, scanning electron microscope (SEM), (EDX), infrared spectroscopy (IR) and electron spin resonance (ESR). Also, spectral distribution of the optical absorbance for the PVC/g-C3N4 nanocomposites films was studied in the wavelength range from 190 to 1100 nm. Thermal stability of the investigated nanocomposites films was investigated by thermal gravimetric analysis technique (TGA). The effect of various concentrations of the g-C3N4 and different doses of gamma-rays on the polymeric matrix and electrical properties of PVC film also has been investigated. The g-C3N4 additives on PVC influenced the crystal structure and optical properties of the nanocomposites films. The nanocomposite film with 10% g-C3N4 achieved higher values of the refractive index and optical conductivity compared with the other films. With different doses of gamma-ray irradiation, the crystal structure and optical properties of PVC/g-C3N4 nanocomposite films were changed in accordance to the cross-linking process within the PVC polymeric chains where a structural rearrangement can be occurred as a result of gamma irradiation. The elemental composition and morphological study of PVC/g-C3N4 nanocomposite films have been checked by the scanning electron microscopy which indicated the homogeneous dispersion of g-C3N4 nanoparticles within PVC network. Finally, electrical properties of PVC/g-C3N4 nanocomposite films with different ratios and distinct gamma doses also have been studied.

Genetic Variability, Heritability and Selection of M2 Sorghum Super 2 Mutant Lines Derived from Irradiation Using Gamma Rays

Sweet sorghum (Sorghum bicolor L. Moench) is a potential plant to be developed as food, feed, and industrial raw materials. In Indonesia, sweet sorghum breeding is needed because only five varieties of sweet sorghum have been released. Genetic variability is essential in breeding. Through mutation induction, breeders can increase genetic variability so that new characters superior to their parents can be obtained. This study aimed to analyze the effect of various doses of gamma-ray irradiation on genetic variability in the agronomic character of the M2 population derived from the sweet sorghum Super 2 mutant and to select potential populations for further selection. The research was carried out at Experimental Garden, ICABIOGRAD, in February-June 2021. The material used was selected M2 mutant seeds from mutant populations resulting from gamma-ray irradiation of sorghum’s shoots of Super 2 variety with doses of 40, 50, 60, and 70 Gy. Variables observed were plant height, stem diameter, panicle length, panicle diameter, sugar content, and fresh and dry panicle weights. The results showed that all radiation doses could increase genetic variability in M2 plants compared to their parents. Significant differences in characters between the original parents and the M2 population with a dose of 40 Gy were seen in the top diameter of the stem, panicle length, and sugar content; at a dose of 50 Gy in panicle diameter, sugar content, and fresh panicle weight; at a dose of 60 Gy on plant height, top stem diameter, sugar content, fresh panicle weight; while at a dose of 70 Gy on bottom stem diameter and middle stem diameter. The potential population for further selection based on fresh weight is the irradiated mutant population with a dose of 70 Gy. In pre-analysis using Cluster Gram and 49 mutant genotypes of the 70Gy M2 population, a group of mutants similar to their parent (Super 2 sorghum variety) and the other group that was completely different from their parent was obtained.

Efek Radiasi Sinar Gamma pada Pertumbuhan Vegetatif Anggrek Vanda Hibrid

Orchids are one of the most important ornamental plants in the world. The existence of natural orchids in their habitat is approaching extinction rate, so it is necessary to increase the diversity of orchids by crossing them. The Vanda orchid is one of the famous orchids in Indonesia because of its uniqueness. Vanda orchids have a very abundant diversity, so they can increase the potential of orchid plants. This study used a hybrid orchid plant &lt;em&gt;Vanda celebica&lt;/em&gt; x &lt;em&gt;Vanda dearei&lt;/em&gt; irradiated by Gamma-rays with a dose of 0 Gray, 10 Gray, 20 Gray, 30 Gray, 40 Gray, and 50 Gray. The data obtained from the observations will be analyzed using descriptive methods by observing each plant in various doses of Gamma-ray radiation compared with control treatment and presented in the form of boxplot images. The irradiation dose of hybrid Vanda orchids (&lt;em&gt;Vanda celebica&lt;/em&gt; x &lt;em&gt;Vanda dearei&lt;/em&gt;) increased the diversity in the parameters of plant height and leaf width. The application of a dose of Gamma-ray irradiation did not cause a significant interaction with the variable number of leaves. The diversity value decreased in the parameters of leaf length and number of roots. Application doses of Gamma-ray irradiation of 10, 20, and 30 Gray can change the leaves into grooves compared to control plants. Mutant plants had lower chlorophyll content than control plants (0 Gray).

Effect of gamma-ray irradiated reduced graphene oxide (rGO) on environmental health: An in-vitro and in-vivo studies

The unique properties of reduced graphene oxide (rGO) have drawn the attention of scientists worldwide since the last decade and it is explored for a wide range of applications. However, the rapid expansion of rGO use in various products will eventually lead to environenal exposure and rises a safety concern on the environment and humal health risk. Moreover, the utilization of toxic chemicals for the reduction of graphene oxide (GO) into rGO is not environmentally friendly, warranting the exploration of non-toxic approaches. In the present work, rGO was synthesized using a different dose of gamma-ray irradiation and characterized. The in-vitro and in-vivo analysis indicated that the gamma-irradiated rGO induced toxicity depending on its degree of reduction and dosage. In the L929 cells, rGO-30 KGy significantly induced cytotoxicity even at low concentration (1 mg L−1) by inducing reactive oxygen species (ROS), lactate dehydrogenase (LDH) enzyme production, nuclear fragmentation and apoptosis. The change in morphology of the cells like membrane blebbing and cell rounding was also observed via FESEM. In the in-vivo model Caenorhabditis elegans, rGO-30 KGy significantly affected the functioning of primary and secondary targeted organs and also negatively influenced the nuclear accumulation of transcription factors (DAF-16/FOXO and SKN-1/Nrf2), neuronal health, and antioxidant defense mechanism of the nematodes. The real-time PCR analysis showed significant up-regulation (ced-3, ced-4, cep-1, egl-1, and hus-1) and down-regulation (ced-9) of the gene involved in germ-line and DNA damage-induced apoptosis. The detailed toxicity mechanism of gamma irradiated rGO has been elucidated. This work highlights the toxicity of rGO prepared by gamma-ray radiation and paves way for understating the toxicity mechanism.

Inducing aluminum oxide growth at room temperature and atmospheric pressure through low dose gamma-ray irradiation

The corrosion resistance of the aluminum is well-known and it is attributed to passivation, a process that occurs when the metal surface reacts to the environment to form a spontaneously thin oxide film. Basically, the natural aluminum oxide film is composed of two layers, an internal layer composed entirely by Al2O3, and a second one made by Al(OH)3. In normal conditions of temperature and pressure, the Al(OH)3 film takes a long time to grow, something around several weeks or months. However, in the present work, through the use of low doses gamma-ray irradiation in an environment composed by air and water vapor, it was possible, in a few days, to increase the layer of Al(OH)3 on a sample of pure aluminum. Using a Cs-137 disk as a gamma-ray source, three aluminum samples were irradiated during 14, 8 and 5 days, receiving absorbed doses of 2.85 mGy, 1.49 mGy and 0.94 mGy, respectively. Comparing the Raman spectrum of the two irradiated samples with another non-irradiated sample, it was possible to verify that the sample irradiated during 14 days had the greatest values of peak intensity and peak area, indicating a higher concentration of aluminum hydroxide when compared to other samples. Moreover, the polarization curves of samples were obtained to analyze the nature of the film formed on the surface. From the results, it was possible to observe that the gamma-ray irradiation led to an improvement in passive film quality (higher resistance), once the irradiation resulted in a lower passivation current density (ipass). To confirm the consistence of previous analysis, more two samples were examined through X-ray photoelectron spectroscopy (XPS), where a sample irradiated during five days showed an increase in the percentage of aluminum hydroxide (related to XPS O 1s peak) in comparison to a non-irradiated sample. Then, it can be pointed that the irradiation, in a low dose, induced the growth of the aluminum hydroxide layer of passive film and improved the film's resistance in a few days. Moreover, the results show the utility of applying low doses of ionizing irradiation to change metal oxide surfaces.

Morphological characters variation of Indonesian accession Echinacea purpurea in response to gamma-ray irradiation

Abstract. Cahyaningsih AP, Etikawati N, Yunus A. 2022. Morphological characters variation of Indonesian accession Echinacea purpurea in response to gamma-ray irradiation. Biodiversitas 23: 5351-5359. Indonesia was one of the countries that introduced E. purpurea as a medicinal plant. Accessions of E. purpurea that have been successfully cultivated in Indonesia have narrow genetic diversity, lack accession variation, and have almost uniform tillers. This study was conducted to determine the effect of different doses of gamma-ray irradiation on morphological characteristics of E. purpurea accession B2P2TOOT. The experimental design was a Randomized Block Design with three replications, and six doses of gamma-ray irradiation (0, 15 Gy, 20 Gy, 25 Gy, 40 Gy, and 60 Gy) were used. The qualitative morphological data were presented descriptively; quantitative data were analyzed using ANOVA followed by a DMRT test at a 5% level with SPSS 16.0 application. The Dice similarity algorithm analyzed the similarity index, group analysis, and dendrogram construction using the UPGMA method with the NTSYS 2.02 application. Gamma-ray irradiation treatment increased the survival rate of E. purpurea plants grown in tropical lowlands. A dose of 15-60 Gy gamma irradiation did not affect the qualitative morphology of E. purpurea roots, stems, and leaves. Irradiation at doses of 40 Gy and 60 Gy resulted in flowers with more variation in color, overall flower shape, and arrangement of ray floret. Gamma irradiation significantly affected plant height, leaf length, leaf area, flower angle, and the first day of flowering. The 40 and 60 Gy doses resulted in longer leaves with wider leaf surfaces. The dendrogram revealed that E. purpurea irradiation resulted in two main groups, with doses of 40 and 60 Gy forming their groups and increasing morphological variation by 30% compared to controls.

The irradiation impacts of high gamma doses on optical features and degradation of Makrofol DE 1-1

The induced impacts of high doses of gamma irradiations on the optical features of the Makrofol DE 1-1 detector were studied in the ultraviolet and visible range (from 270 to 500 nm). Makrofol DE 1-1 detector specimens were irradiated separately for different doses from 200 to 1000 kGy; step 200. The optical absorbance spectra of the pristine Makrofol DE 1-1, as well as the irradiated gamma-ray samples display two main features: (i) A redshift with further gamma-ray irradiation doses from 200 to 1000 kGy. This redshift can be ascribed to irradiation-induced defects in polymer material. (ii) A remarkable increment in the optical absorbance for irradiated Makrofol DE 1-1 specimens compared to the pristine one. This increment can be ascribed to the creation of some electronic levels within the forbidden gap resulting from the irradiation process. Moreover, this absorbance increment was employed to assess the degradation percent produced by gamma-ray irradiations. The degradation percent of the Makrofol DE 1-1 increased from 31.73% at 200 kGy to 78.08% at 1000 kGy. The optical band gap, Fermi level and metallization criterion showed decrement behaviors with further doses of gamma-ray irradiations. Also, the percent of changes in optical band gap values were employed to evaluate the degradation of Makrofol DE 1-1 under gamma-ray irradiations. This percent augmented from 15.19% at 200 kGy to 20.25% at 1000 kGy proving the obvious degradation of Makrofol DE 1-1 under gamma-ray irradiations. On the other hand, the number of carbon atoms per cluster, linear and nonlinear refractive indices showed increasing behaviors with further doses of gamma-ray irradiations.

Enhancing the electrical properties of graphite nanoflake through gamma-ray irradiation

Understanding changes in material properties through external stimuli is critical to validating the expected performance of materials as well as engineering material properties in a controlled manner. Here, we investigate a change in the c-axis electrical properties of graphite nanoflakes (GnFs) induced by gamma-ray irradiation, using conductive probe atomic force microscopy (CP-AFM). The fundamentals behind the change in their electrical properties are elucidated by analyzing the interlayer spacing, graphitization, and morphology. An increase in gamma-ray irradiation dose for GnFs leads to an exponential increase in the electrical conductance and a gradual decrease in the interlayer spacing, while accompanying indistinguishable changes in their morphology. Our experimental results suggest that the c-axis electrical conductance enhancement of GnFs with gamma-ray irradiation might be attributed to a reduction in interlayer spacing, though the created defects may also play a role. This study demonstrates that gamma-ray irradiation can be a promising route to tailor the electrical properties of GnFs.