A low-energy single ion irradiation system is developed in its initiation in Thailand to follow one of the trends in novel ion beam technology exploitation. Single ion irradiation of materials is a highly technological development of ion beam technology. The developed single ion irradiation systems worldwide are primarily in the MeV-energy range and for single cell studies, and recently the trend has been extended to the low-energy range (< 100 keV) but focused on microelectronic applications. Based on our previous research on low-energy ion beam irradiation of biological cells and DNA, we design and simulate a low-energy single ion implantation system, aiming at eventual construction of such a novel ion beam apparatus for applications to the biological studies. In the system, the ion energy is decreased to orders < 1 keV by the existing deceleration lens, then the low-energy ion beam passes through µm slits, and finally, low-energy single ions are obtained by beam scanning with appropriate frequencies from scanner plates and detected by a single ion detection device. Conceptual design, calculation and simulation of this single ion system are presented.

Plasma technology has recently been one of the potential candidates for the targeted treatment of cancers. In this work, Nightingale ® , a non-thermal air plasma jet device, was used to activate lactated Ringer’s injection (LRI) for the in vitro inactivation of lung cancer cells—A549 and H1299. The optimal treatment condition and its effects on the cell cytotoxicity of lung cancer cells were evaluated. Optical emission spectroscopy (OES) and gas detection results indicated gas phase reactive oxygen and nitrogen species (RONS) can be controlled and precisely calculated from plasma dissipated power. For plasma-activated LRI (PA-LRI), concentrations of H 2 O 2 , NO 3 − , and NO 2 − , as well as their shelf lives, were investigated. Two-hour treatment of PA-LRI on A549 and H1299 cells resulted in 92% and 70% cell death, respectively. While the non-cancerous cell, human lung fibroblast (HLF), was not affected neither in terms of cell death or morphological change. To elucidate the mechanisms of the tumor cell cytotoxicity induced by PA-LRI, common active species generated in PA-LRI (H 2 O 2 , NO 2 − , NO 3 − ) were tested. Results showed that H 2 O 2 alone can induce 72% of cell death, compared to PA-LRI, while it was 19% and 2% for NO 2 − and NO 3 − respectively. The addition of catalase, which degrades H 2 O 2 , reduced cell death induced by PA-LRI and H 2 O 2 to 9% and 6%, respectively. These suggest H 2 O 2 is the main player in PA-LRI-induced lung cancer cell death in vitro. Our discoveries not only benefit the effective usage of plasma-activated LRI but also the applications of plasma technology in medical fields.

A project on the development of midinfrared free‐electron laser and terahertz (THz) radiation produced by a home‐constructed electron accelerator has recently been launched in the laboratory. A study of THz technology and its applications for biology is one of the emphases and thus THz safety is in focus. This is not only due to the THz radiation itself, but also its association with 5G safety, which has recently become a topic of public concern worldwide. If THz radiation is demonstrated safe, 5G, with the same power, should be safe due to its lower photon energy. The safety issues of both radiations are discussed with different opinions. Herein, safety from physics is discussed and it is pointed out that radiation safety not only depends on photon energy but also radiation power, or the photon dose rate. Through quantitative discussion of the currently used 5G transmission station power, this study confirms that 5G is safe, while THz safety is not yet certain. Therefore, measurement of THz power, a test of THz radiation effect on DNA change, an investigation of the DNA vibration using the THz time‐domain spectroscopy, and molecular dynamics simulation of THz radiation of DNA are suggested.

Maintaining agro-food product safety remains a significant challenge for satisfying local and global consumers in tropical countries. This issue has been growing due to new pathogen strains, low infectious doses, increased virulence, antibiotic resistance, cross-contamination or recontamination of foods, food-contact surfaces, and biocontamination of water within the food production chain. To respond to this situation, we studied the inac-tivation efficacy of surface dielectric barrier discharge (SDBD) plasma against pathogens on the surface of various pork cut parts, including the loin, hip, belly, liver, and intestine. The SDBD plasma was operated at 0.30 W/cm2 in ambient air, with a gap of 5.0 mm between the plasma generator and the sample surface. Up to 96% germicidal efficiency against surface pathogens were observed, showing after 1 min of SDBD plasma exposure. Visualization of reactive species deposition on the treated surface using KI-starch agar gel reagent indicated a non-uniform distribution of the SDBD-generated reactive species on the treated surface. Following the indirect plasma treat-ment by the SDBD reactor, the overall color of pork cut samples after plasma treatment was significantly different compared with before. However, the surface morphology and structural characterization of the treated pork cut samples were not significantly altered, and residual nitrites and nitrates were lower than the restriction level for safe consumption. The SDBD reactor should be developed further to produce a uniform distribution of reactive species on the meat surface for the improvement of the decontamination effect without undesirable effects on meat quality parameters.

A tapered glass capillary MeV-ion microbeam setup, previously home-developed, was recently upgraded. To check the upgraded microbeam system quality and accuracy, microbeam particle induced X-ray emission (PIXE) mapping of potassium permanganate (KMnO4) solution diffusion in filter paper was carried out to study how the measured solvent diffusion followed the diffusion laws. Two initial boundary conditions and diffusion situations were applied: (1) the paper vertically placed in air with one end soaked in the solution for ten minutes, and (2) the paper horizontally placed on water with the solution dropped at a side of the paper for three minutes. 2-MeV-proton microbeam PIXE analyzed the paper pixel by pixel and the GUPIXWIN software was used to calculate the elemental concentrations in the pixels to map the concentration changes in the pixels as a function of the distance between the pixel position and the origin of the solution. The resulting maps demonstrated the solution diffusions in two cases indeed well following the diffusion laws, a steady-state diffusion dominated process where the elemental concentration was a linear function with the distance but joined by other non-diffusion factors for case 1, and a pure diffusion process where the elemental concentration was an error function with the distance for case 2.

We conducted a series of fundamental research-based experimentations to measure the X-ray production cross sections of K-, L-, and M-shells from thick samples of Cu, Ag and Au, respectively, for proton beam in a lower energy range of 0.7 - 3.5 MeV utilizing particle induced X-ray emission (PIXE) analysis. The measurement theories based on the Merzbacher-Lewis (ML) relationship and procedure for thick samples are described. The detector efficiency and system calibration were first measured from Fe-55 and Am-241 X-ray sources and the standard sample, respectively. The X-ray yields as a function of the proton energy were measured and fitted for finding the derivatives which were used for the cross section measurement. The obtained results were compared with published data and predictions from the theoretical models of Plane Wave Born Approximation (PWBA) and the advanced ECPSSR. The measured results from Cu were in good agreement with the theoretical predictions, especially in the lower energy regime, and most of the reported data, while for the higher energy regime deviated by a few times but still in the same order of magnitude with the theoretical data. The Ag and Au results were in excellent agreement with published and theoretical values.

Particle induced X-ray emission (PIXE) is a powerful ion beam analysis tool which is capable of determining elemental species and concentrations in various materials in superior sensitivity and resolution. PIXE analysis of biological living materials is ever an interesting and challenging topic due to more complexity of the materials than conventional solids. In this presentation we report our home-developed 1.7 MV tandem accelerator based PIXE technique and its application in analysis of Thai local biosamples to determine the elements, concentrations and even areal distributions to serve our local research. The samples included rice grains, including ion-beam-induced mutants, human blood and cardiac muscle cells, and plant tissues. In most analyses, traditional 2 MeV proton beam was used, but in some particular cases, 1 MeV heavy carbon beam was also used. The elemental concentrations were determined from the PIXE spectra using the GUPIX software with special biomaterial concerns. In determination of the areal elemental concentration distribution, we utilized home-developed glass capillary microbeam technique to scan the sample surface area of interest. Various results of the particular biosamples are reported and discussed.

To respond to the global warming challenge to local agriculture, we applied a low-energy heavy ion beam as novel biotechnology to improve crop drought tolerance. Dehulled seeds of Thai Jasmine rice, Khao Dawk Mali 105 (KDML105), a popular Thai rice variety, were bombarded by a nitrogen ion beam with energy of tens-keV and fluences in an order of 1016 ions/cm2. The resulting mutagenized rice was obtained, selected, and further advanced until phenotypically stable. Mutagenized lines were screened for drought tolerance in the seedling and reproductive stages under an artificially created drought condition in comparison with KDML105 and the drought-tolerant reference variety, CT9993, using both subjective and quantitative parameters. We advanced the mutants up to M8 generation for stabilization and found a mutant line named HyKOS22, which displayed higher tolerance to the drought condition than KDML105 and CT9993 and produced a higher crop yield than KDML105. Genetic changes in HyKOS22 were confirmed by molecular biology analysis.

In our practice of applying GUPIXWIN software in calculations of the trace element concentrations in biosamples measured by particle induced X-ray emission (PIXE) technique, we found that the calculated concentration data critically depended on the program setup and experimental parameters input to the software. Dependences on some important setups and parameters such as the solution types (i.e. Trace element solution in a known matrix and Iterative matrix element solution), matrix composition, detector parameters (e.g. window thickness), sample structure, normalization, etc., which are sometimes easily not paid with intensive attention by users, are analyzed and discussed utilizing our PIXE spectra of some biosamples. We found that most parameters or program setups were critical to affect the calculated results, but some such as normalization was not. We also found that if only relative trace element concentrations instead of their absolute values are concerned, different program setup solutions resulted in similar data. We conclude that meticulous care must be taken in selection of the experimental parameters and setup conditions in using GUPIXWIN to make correct calculations of the trace element concentrations in biological or organic samples.

In development of plasma biotechnology for applications in agriculture and medicine, we investigated plasma treatment effects on crop seeds. Sunflower seeds were treated with three different types of plasma, i.e. low-pressure plasma, dielectric barriers discharge plasma and jet plasma. The plasma was characterized using optical emission spectroscopy for understanding of physical and chemical species in the plasma. Plasma-treated seeds were studied for the plasma effects on both physical and biological properties, including the surface morphology and roughness, contact angle, water absorption rate, germination rate, survival rate and growth rate, etc. In general, with increasing of the plasma power, the seed surface roughness increased, the contact angle decreased and thus the wettability increased, the water absorption depended on the power, and the germination and growth rates increased to maximum under certain plasma parameters. The plasma bioeffects are discussed in association with the physical effects.

Previously, a novel compact low-temperature plasma jet device with adjustable pulse-parameters was developed to use ambient air as a plasma source for the inactivation of chronic wound bacteria. Its adjustable burst-mode pulse was proved to be highly beneficial for the controllable generation of the desired reactive oxygen and nitrogen species. In this study, further bactericidal effects and its safety on human dermal fibroblasts (HDF) were investigated. The generated plasma inactivated Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) effectively in a time- and dose-dependent manner. Quantification of colony-forming units from bacterial biofilms confirmed the elimination of biofilms formed by PA or SA. Next, HDF cells were plasma-treated and the morphology was observed using an inverted microscope and a scanning electron microscope. No particular morphological changes were observed on cell membrane and cell attachment. MTT assay of the HDF cells after plasma exposure also confirmed the functional enzymatic activity of the cells up to 5 min of treatment. Flow cytometric assay for annexin V and 7-AAD showed that plasma exposure did not significantly induce apoptosis or necrosis of the cell. Intracellular nitric oxide, reactive oxygen species, and Ki-67 protein, a marker for cell proliferation, were also measured by flow cytometry. Intracellular levels of nitric oxide significantly increased, while reactive oxygen species and Ki-67 protein showed no significant alteration after the plasma exposure. Taken together, we demonstrated that the newly developed adjustable-pulse low-temperature air plasma jet device was an effective tool for the elimination of bacteria especially on chronic wound, where the treatment is needed to be least invasive and safe for the surrounding tissue.

Commercial dielectric barrier discharge plasma jet (DBDPJ) with helium gas was used as a handy cold atmospheric pressure plasma tool to study the DBDPJ effects on contaminated wound healing. The contaminated wound was modeled into three parts: bacteria as the contaminant origin, bacterial biofilm as the simulated bacterial contaminant layer on the wound, and the wound cells. The bacteria were Staphylococcus aureus and Pseudomonas aeruginosa and the wound cells were human dermal fibroblasts adult (HDFa) cell. DBDPJ treatments were carried out on the three model parts respectively to study the DBDPJ effects on bactericidal and wound cell survival as functions of the plasma conditions including the plasma dissipated power and exposure time and the role played by the plasma radical species. The results demonstrated that DBDPJ could effectively kill the bacteria without significant side effect on the HDFa cell. Optimal plasma conditions were determined and are ready for clinical uses.

The work was aimed at using Geant4-DNA software to simulate ultra-low-energy particle irradiation of DNA to understand relevant effects and fundamentals on DNA strand breaks. Light particle species of electron, hydrogen, proton, helium (He), He+ and He2+ with energy ranged in 10 - 1000 eV and fluence varied from 5 x 10(3) to 1 x 10(5) particles/cm(2) irradiated DNA models, poly-AT, poly-CG and pGFP. The irradiation effect on DNA single strand breaks (SSBs) and double strand breaks (DSBs), particularly the latter, was focused. Results showed that the ratios between the numbers of SSBs and DSBs were nearly the same, independent of the particle energy and fluence. DSBs increased with increasing of ion energy, but not depended on the fluence. Discrepancies between the simulation and experiments were discussed, attributed to the simulation code overlooking the direct interaction of elastic collision between the particle and the DNA atom to cause atomic displacement.

MeV-ion microbeam using the capillary technique was home-developed based on the 1.7-MV tandem accelerator and beamline at Chiang Mai University. The system consisted of the capillary itself, a capillary holder, a holder swing mechanism, and a system support frame with a micrometer for vertical micro-adjustment. The glass capillaries had various sizes in a range of 10 – hundreds μm in the exit inner diameter. In this study, the capillary ion-microbeam was applied in elemental concentration distribution mapping of plant leaves using particle induced X-ray emission (PIXE) analysis. The interests were focused on difference in the elemental concentrations distributed between the leaf vein and lamina of local longan leaves which were sprayed by chemical fertilizer and pesticide and leaves of Peperomia pellucida, a herb, which was cultured by dissolved supplement solution of various nutrients. 1D and 2D maps of detected elements from the longan and herb leaves across vein and lamina were generated respectively, showing redistributions of the elements between vein and lamina due to the human activities. Details of the mapping results are reported and discussed.

Experimental observation has shown that in the use of low-energy ion beams for living biological material modification, the ion beam fluence required to induce cell mutation is orders of magnitude greater than the cell lethal dose. This seems contradictory to a simplistic perception that DNA modification should be proportional to radiation dose, and thus that high dose irradiation should cause a high degree of damage to DNA, leading to cell death, while the more limited DNA damage produced by relatively low dose irradiation should enable cell mutation. Here we suggest an answer to this puzzle from the perspectives of both physics and biology. Key points include the physical differences between high-energy ionizing irradiation and low-energy ion beam irradiation, and the cell’s non-linear response to exogenous physical actions. Low-energy ion beam processes are dominated by nuclear interactions while the effects of high-energy ionizing irradiation are dominated by electronic interactions, in addition to the energy differences leading to different modification depths depending on what kind of radiation is applied. The response of living cells to ion beam bombardment is different from that of non-biological solid material, the former having a special suicide mechanism to protect the cell from being modified or mutated while the latter responds monotonically. Only when the ion beam fluence/dose increases to a level such that adjacent atoms in DNA double strands are displaced, do irreversible double strand breaks (DSBs) dominate the DNA damage so that mutation can occur. We can estimate this fluence/dose level, which turns out to be in good agreement with experimentally determined values.

The work was aimed at using gas to cool the secondary ions emitted from gas cluster ion beam (GCIB) bombardment of biosamples for lowering the ion energy distribution and thus enhancing the detection sensitivity for secondary ion mass spectrometry (SIMS). An Ar-cluster ion source at energy in an order of keV was installed with the Q-ToF (Quadrupole Time-of-Flight) premier at the Quantum Science and Engineering Center, Kyoto University. The main component of the Q-ToF premier consisted of a travelling-wave ion guide, a mass filter quadrupole lens, a travelling-wave collision cell, and a ToF analyzer. A 1,2-Distearoyl-sn-glycero-3-phosphocholine (DSPC) sample was used in the study on cooling the secondary ions at the travelling-wave ion guide by using helium and molecular nitrogen gas. The DSPC sample was impinged with primary Ar-cluster ions at energy 10 keV and sputtered for secondary ions in an energy range from zero to several hundred eV. Sputtering emitted secondary ions were extracted to the Q-ToF mass spectrometer. The experiment was carried out to measure DSPC secondary ion mass spectra in two modes at varied pressures of helium or molecular nitrogen gas. The first mode was the MS mode and the other was the MS/MS mode which defined the m/x = 790.6 Da for the protonated molecule at the mass filter quadrupole lens. The experiment found that the secondary ion yields (SIYs) in the MS mode reached the maximum at 2.0 and 0.35 Pa for helium and molecular nitrogen, respectively. In the MS/MS mode, the SIYs reached the maximum at 2.5 and 0.35 Pa for helium and molecular nitrogen, respectively, and however, some fragments could not be eliminated by the cooling molecular nitrogen gas. The cooling of the secondary ions for lowering the energy distribution and the transverse direction of the secondary ions by using helium was more effective and stable than by using molecular nitrogen.

Low-energy ion beam served as a novel mutation induction tool treated seeds of red, low-amylose and non-aromatic Sangyod Phatthalung rice (Oryza saliva L. cv. Sangyod Phatthalung) for new mutant rice lines, specifically suited to the rice vermicelli production. Seven thousand dehulled rice seeds were bombarded with 50-kV-accelerated mixed nitrogen ions to a fluence of 4 x 10(16) ions/cm(2). Seven stable photoperiod-insensitive lines were obtained and studied for their agricultural traits, grain characteristics related to the rice vermicelli production and to confirm their genetic changes. Primarily, these mutants were shorter and produced a higher number of panicles than the wild-type. After 4-month storage, the flour obtained from the mutants exhibited better water absorption index and pasting properties, resulted in an increased rice vermicelli production yield. Genotypic changes in the mutagenized lines were confirmed. The results demonstrated that low-energy N-ion beam irradiation could induce rice mutations to benefit food industry.

Thai jasmine rice was improved by low-energy heavy-ion beam induced mutation breeding for high yields. Seeds of Thai rice KDML105 and its ion-beam-induced primary mutant BKOS6 were bombarded by mixed atomic and molecular nitrogen ions accelerated by tens kV in a home-developed high-current ion implanter. Both phenotypes and genotypes of induced mutants were investigated. In M1 generation, more than a hundred plants with the photoperiodinsensitivity potential were obtained. In the subsequent generations, tens of rice mutants with a broad spectrum of phenotypic variations dominantly supporting the high yield potential were selected and studied for the mutation stability till M5 generation. The mutants possessed not only high crop yields but also other properties improved or altered in the grains. DNA fingerprinting analysis revealed polymorphisms in the mutants distinguished from that of KDML105. The cDNA fingerprinting investigation indicated four additional fragments in the mutant profiles encoding proteins which could be involved in the high yield characteristics of the mutants.

We have carried out a series of experiments on the ultra-low-energy ion beam bombardment of naked DNA to study the final stages of interaction between energetic ions and biological molecules and atoms. A carbon ion beam (carbon is the ion species usually used for cancer therapy) was used to bombard naked plasmid DNA pGFP to fluences of 1 x 10(15), 2 x 10(15) and 4 x 10(15)ions/cm(2) at the ultra-low energy of 50, 100 and 300 eV, or similar to 10 eV/amu. Modification of the DNA in terms of topological form changes was investigated using gel electrophoresis. We find that there is a threshold of ion beam conditions for occurrence of the linear form indicating DNA double strand breakage (DSB), which is the dominant course for cell mutation or lethality. DNA DSBs can be brought about by carbon ion bombardment at the lowest ion energy of 50 eV and fluence of 4 x 10(15)ions/ cm(2), or at the higher energy of 100 or 300 eV and the lowest fluence of 1 x 10(15)ions/cm(2). We discuss the origin of these threshold conditions using a simplified DNA double strand model as well as in terms of the chemical activity of carbon.

Particle-Induced X-ray Emission (PIXE) using heavy ions proved to be an alternative with respect to PIXE using light protons due to relatively large cross sections. In this work we explored the capabilities of PIXE with using singly-charged carbon ions at relatively low energy of 1 MeV (or 83 keV/amu) to measure K alpha X-ray production cross sections. The measurement was performed for thick samples of Si, Fe, Cu and Zn, using the standard 2-MeV proton-induced cross sections as the reference. For the measurement from thick samples, we adopted a special multi-slabs method in the calculation by considering the sample thickness effect. The effective ion range was divided into a number of thin slabs in which the energy dependent cross section and the thickness dependent Xray transmission were varied. The paper describes details of the measurement principle and method and reports the result. The resulting data obtained from the present work were compared with those from the PWBA and ECPSSR theories, the simple thin-film method and the measurement of thin film samples and discussed for the validity of our result.