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Injecting high-energy heavy ions in the electronic stopping regime into solids can create cylindrical damage zones called latent ion tracks. Although these tracks form in many materials, none have ever been observed in diamond, even when irradiated with high-energy GeV uranium ions. Here we report the first observation of ion track formation in diamond irradiated with 2-9 MeV C60 fullerene ions. Depending on the ion energy, the mean track length (diameter) changed from 17 (3.2) nm to 52 (7.1) nm. High resolution scanning transmission electron microscopy (HR-STEM) indicated the amorphization in the tracks, in which π-bonding signal from graphite was detected by the electron energy loss spectroscopy (EELS). Since the melting transition is not induced in diamond at atmospheric pressure, conventional inelastic thermal spike calculations cannot be applied. Two-temperature molecular dynamics simulations succeeded in the reproduction of both the track formation under MeV C60 irradiations and the no-track formation under GeV monoatomic ion irradiations.
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BACKGROUND: Muscle response in older adults is believed to decrease with maximal muscle strength, although it has not been adequately assessed; further, the relationship between frailty and muscle response remains unexamined. OBJECTIVES: This study aimed to develop a practical method for measuring muscle response using grip strength in older adults and to clarify the relationship between frailty and grip strength response. DESIGN, SETTING, AND PARTICIPANTS: We performed a cross-sectional, clinical, observational study. A total of 248 patients (94 men and 154 women, mean age: 78.2 years) who visited the outpatient unit in the Integrated Healthy Aging Clinic of our Hospital for the first time were enrolled. MEASUREMENTS: Using a grip strength measuring device originally developed by us, we measured grip strength response indices, such as reaction time, time constant, rate of force development (response speed), and maximum grip strength. Grip strength response indices were compared among three groups (robust, pre-frail, and frail) according to the Fried and Kihon checklist assessments for frailty. RESULTS: Based on Fried's assessment, marked differences were found between groups not only in maximal grip strength but also in response time and response speed. Based on the Kihon checklist assessment, there was no significant difference in response time; however, a considerable difference in response speed for the left hand was observed. Moreover, according to the Kihon checklist assessment, some cases showed differences in muscle response although not in maximal muscle strength. CONCLUSIONS: The response speed of grip strength was suggested to decrease with frailty. The results suggest that measurement of grip strength response in both hands is useful to examine the relationship between frailty and grip strength response.
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Fragilidad , Masculino , Anciano , Humanos , Femenino , Fragilidad/diagnóstico , Tiempo de Reacción , Anciano Frágil , Estudios Transversales , Evaluación Geriátrica/métodos , Fuerza de la ManoRESUMEN
First of all, this article aimed to evidence the role of a modified printer developed for continuous carbon fibre reinforced PolyAmide (cCF/PA6-I) together with the use of a fully open slicing step on the printing quality and the longitudinal/transverse tensile and in-plane shear properties. A comprehensive assessment of the microstructure and properties with a similar material (cCF/PA6-I), but produced with a commercial printer (i.e., Markforged® MarkTwo) has been achieved. Our customised printer and the open slicer used have made possible to better control the print conditions (i.e., layer height and distance between filaments), to reduce the porosity from more than 10% to about 2% and improve the mechanical properties. Moreover, the understanding of the behaviour of these 3D printed composites with wide-ranging external temperatures is mandatory for future use in a severe environment and/or development of new thermally active 4D printed composites. The 3D printed cCF/PA6-I composites have been then thermomechanically characterised along different printing directions (0, 90 and ± 45°) from -55 to +100 °C. Unlike the longitudinal properties that hardly change with temperature, the transverse and in-plane shear stiffness and strength of these 3D printed composites were particularly sensitive to temperature variations, with decreases of 25-30% and 30-55%, respectively. This was due to the high sensitivity of the polymer matrix, the fibre/matrix and interfilament interfaces when the composites were loaded along those directions, because damages induced by internal thermal stresses. Fractography has also been carried out to reveal damage mechanisms.
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AIMS: Although palliative radiotherapy for gastric cancer may improve some symptoms, it may also have a negative impact due to its toxicity. We investigated whether symptoms improved after radiotherapy with adjustment for the Palliative Prognostic Index (PPI) considering that patients with limited survival tend to experience deterioration of symptoms. MATERIALS AND METHODS: This study was an exploratory analysis of the Japanese Radiation Oncology Study Group study (JROSG 17-3). We assessed six symptom scores (nausea, anorexia, fatigue, shortness of breath, pain at the irradiated area and distress) at registration and 2, 4 and 8 weeks thereafter. We tested whether symptoms linearly improved after adjusting for the baseline PPI. Shared parameter models were used to adjust for potential bias in missing data. RESULTS: The present study analysed all 55 patients enrolled in JROSG 17-3. With time from registration as the only explanatory variable in the model, a significant linear decrease was observed in shortness of breath, pain and distress (slopes, -0.26, -0.22 and -0.19, respectively). Given that the interaction terms (i.e. PPI × time) were not significantly associated with symptom scores in any of the six symptoms, only PPI was included as the main effect in the final multivariable models. After adjusting for the PPI, shortness of breath, pain and distress significantly improved (slope, -0.25, -0.19 and -0.17; P < 0.001, 0.002 and 0.047, respectively). An improvement in fatigue and distress was observed only in patients treated with a biologically effective dose ≤14.4 Gy. CONCLUSION: Shortness of breath, pain and distress improved after radiotherapy. Moreover, a higher PPI was significantly associated with higher symptom scores at all time points, including baseline. In contrast, PPI did not seem to influence the improvement of these symptoms. Regardless of the expected survival, patients receiving radiotherapy for gastric cancer can expect an improvement in shortness of breath, pain and distress over 8 weeks. Multiple-fraction radiotherapy might hamper the improvement in fatigue and distress by its toxicity or treatment burden.
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Oncología por Radiación , Neoplasias Gástricas , Humanos , Pronóstico , Neoplasias Gástricas/complicaciones , Neoplasias Gástricas/radioterapia , Cuidados Paliativos , Fatiga/etiología , Dolor/etiología , Dolor/radioterapia , Dolor/diagnóstico , Disnea/etiología , Disnea/radioterapiaRESUMEN
INTRODUCTION: Many patients experience anxiety, not limited to claustrophobia, before magnetic resonance imaging (MRI) examination. We performed a non-randomized controlled trial to evaluate whether a patient-friendly audiovisual (AV) system in the MR scanner room reduces patient anxiety. METHODS: We randomly selected 61 participants from outpatients who required brain MRI examination. Patients were informed that they could choose to undergo an MRI examination with a patient-friendly AV system (Ambient Experience, Philips Healthcare, Best, The Netherlands) or the standard system. To complete the MRI examination without affecting clinical practice, all patients who preferred the patient-friendly AV system were assigned to the preferring AV group. Patients who indicated that either system was acceptable were randomly assigned to the no preference but allocated AV group or control (using the standard system) groups. In both groups, state anxiety using the State-Trait Anxiety Inventory (STAI) was assessed before and after the MRI examination (A-State-before and A-State-after MRI, respectively). The changes in A-State-before and A-State-after MRI were categorized as follows: relieved high-state anxiety, no change in high-state anxiety, stable easiness, and intensified anxiety. RESULTS: Among the 61 included patients, 19 were assigned to the preferring AV group, 20 to the no preference but allocated AV group, and 22 to the control group. There were no significant differences between the group. However, in patients with high-state anxiety before MRI, the preferring AV group and the no preference but allocated AV group, which used the patient-friendly AV system, relieved high-state anxiety by 63.6% (7 of 11 patients) and 81.8% (9 of 11 patients), respectively. In contrast, the control group using the standard system relieved high-level anxiety by only 42.9% (three out of seven patients). CONCLUSION: The patient-friendly AV system may reduce anxiety in patients undergoing MRI examinations. IMPLICATIONS FOR PRACTICE: The patient-friendly AV system may reduce anxiety in patients undergoing MRI examination by providing a more patient-centered MRI examination environment. These findings may help ameliorate negative perceptions associated with MRI examination.
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Ansiedad , Imagen por Resonancia Magnética , Humanos , Imagen por Resonancia Magnética/métodos , Países BajosRESUMEN
Damaged regions of cylindrical shapes called ion tracks, typically in nano-meters wide and tens micro-meters long, are formed along the ion trajectories in many insulators, when high energy ions in the electronic stopping regime are injected. In most cases, the ion tracks were assumed as consequences of dense electronic energy deposition from the high energy ions, except some cases where the synergy effect with the nuclear energy deposition plays an important role. In crystalline Si (c-Si), no tracks have been observed with any monomer ions up to GeV. Tracks are formed in c-Si under 40 MeV fullerene (C60) cluster ion irradiation, which provides much higher energy deposition than monomer ions. The track diameter decreases with decreasing the ion energy until they disappear at an extrapolated value of ~ 17 MeV. However, here we report the track formation of 10 nm in diameter under C60 ion irradiation of 6 MeV, i.e., much lower than the extrapolated threshold. The diameters of 10 nm were comparable to those under 40 MeV C60 irradiation. Furthermore, the tracks formed by 6 MeV C60 irradiation consisted of damaged crystalline, while those formed by 40 MeV C60 irradiation were amorphous. The track formation was observed down to 1 MeV and probably lower with decreasing the track diameters. The track lengths were much shorter than those expected from the drop of Se below the threshold. These track formations at such low energies cannot be explained by the conventional purely electronic energy deposition mechanism, indicating another origin, e.g., the synergy effect between the electronic and nuclear energy depositions, or dual transitions of transient melting and boiling.
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We report the elongation of embedded Au nanoparticles (NPs) in three different matrices, i.e. amorphous carbon (a-C), crystalline indium tin oxide (InxSn1-xOz; ITO) and crystalline calcium fluoride (CaF2), under irradiations of 4 MeV C60 + cluster ions and 200 MeV Xe14+ ions. Under 4 MeV C60 cluster irradiation, strong sputtering is induced in CaF2 layer so that the whole the layer was completely lost at a fluence of 5 × 1013 ions cm-2. Au NPs were partly observed in the SiO2, probably due to the recoil implantation. Amorphous carbon (a-C) layer exhibits low sputtering loss even under 4 MeV C60 irradiation. However, the elongation in a-C layer was low. While the ITO layer showed a certain decrease in thickness under 4 MeV C60 irradiation, large elongation of Au NPs was observed under both 4 MeV C60 and 200 MeV Xe irradiation. The ITO layer preserved the crystallinity even after large elongation was induced. This is the first report of the elongation of metal NPs in a crystalline matrix.
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This study reports that high fluence fullerene ion (C60+) irradiation of 1-6 MeV, which was made possible by a new-type of high-flux ion source, elongates metal nanoparticles (NPs) in amorphous SiO2 as efficiently as swift heavy ions (SHIs) of 200 MeV Xe14+, i.e., two orders of the magnitude higher energy ions. Comparing the irradiation effects induced by both the beams, the stopping processes of C60 ions in SiO2 are discussed in this paper. Despite of having almost the same elongation efficiency, the C60+ irradiation induced ~10 times more efficient sputtering due to the clustering enhancement and/or the synergy effect. Ion tracks of ~10.4 nm in diameter and 60-80 nm in length were observed in crystalline SiO2 under 4 MeV C60 irradiation. While the track diameter was comparable to those by SHIs of the same electronic stopping, much shorter track lengths than those predicted by a rigid C60 molecule model indicates that the fragmentation occurred due to nuclear collisions. The elongation of the metal NPs was induced only down to the depth where the tracks were observed but not beyond.
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BACKGROUND/AIM: The mouse vagina exhibits stratified squamous epithelium, which is comprised of multiple cell layers. We previously showed that erbB signaling, induced by epithelial estrogen receptor 1 (ESR1), is required for the initial differentiation of the epithelium. However, the downstream effector that mediates terminal differentiation in the apical layers remains elusive. The contribution of fibroblast growth factor (FGF) to vaginal epithelial cell differentiation was investigated. MATERIALS AND METHODS: Vaginas from wild-type or epithelium-specific Esr1 conditional knockout (cKO) mice were analyzed using immunohistochemistry and quantitative real-time RT-PCR. RESULTS: Of the FGF ligands examined, Fgf22 mRNA was significantly induced following estrogen treatment. Furthermore, FGF downstream signaling, phosphorylated FRS2 and ERK1/2 were exclusively expressed in the apical layers of the vaginal epithelium. No changes in such expression were observed in the Esr1 cKO mice. CONCLUSION: FGF-ERK/MAPK pathway may be a main inducer of terminal differentiation in the mouse vaginal epithelium.
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Diferenciación Celular , Células Epiteliales/citología , Células Epiteliales/metabolismo , Factores de Crecimiento de Fibroblastos/metabolismo , Membrana Mucosa/citología , Membrana Mucosa/metabolismo , Vagina , Animales , Biomarcadores , Diferenciación Celular/genética , Femenino , Ligandos , Ratones , Ratones Transgénicos , Transducción de SeñalRESUMEN
BACKGROUND/AIM: Despite intensive chemotherapy, the survival rates for high-risk neuroblastoma, most of which have MYCN amplification, remain low. Overexpression of N-myc oncoprotein promotes expression of cancer-associated properties. We recently found that combination of all-trans retinoic acid (ATRA) with the ß1-integrin-activating peptide TNIIIA2 attenuated cancer-associated properties of neuroblastoma cells through N-Myc degradation. However, ATRA has serious side-effects and there are concerns about late adverse effects. The aim of this study was to examine the effects of the combination of acyclic retinoid (ACR) with TNIIIA2 on neuroblastoma. MATERIALS AND METHODS: The effects of ACR and TNIIIA2 were examined by neuroblastoma cell proliferation and survival assays as well as by using a neuroblastoma xenograft model. The levels of N-Myc and cancer-associated malignant properties were assayed by western blot and colony formation assay, respectively. RESULTS: Combining ACR, which is clinically safe, with TNIIIA2 induced proteasomal degradation of N-Myc and reduction of neuroblastoma cell malignant properties. An in vivo experiment showed therapeutic potential. CONCLUSION: ACR-TNIIIA2 combination treatment may be efficacious and clinical safe chemotherapy for high-risk neuroblastoma.
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Antineoplásicos/uso terapéutico , Proteína Proto-Oncogénica N-Myc/metabolismo , Neuroblastoma/tratamiento farmacológico , Péptidos/uso terapéutico , Tenascina/uso terapéutico , Tretinoina/análogos & derivados , Animales , Antineoplásicos/farmacología , Proliferación Celular/efectos de los fármacos , Ratones Endogámicos BALB C , Ratones Desnudos , Neuroblastoma/metabolismo , Neuroblastoma/patología , Péptidos/farmacología , Fenotipo , Tenascina/farmacología , Tretinoina/farmacología , Tretinoina/uso terapéutico , Carga Tumoral/efectos de los fármacosRESUMEN
OBJECTIVE: Guided self-help treatments based on cognitive behavioral therapy (CBT-GSH) are regarded as a first-line effective treatment for bulimia nervosa (BN). With limited application for CBT-GSH in Japanese clinical settings, we conducted a single arm pilot study in order to confirm the acceptability and availability of CBT-GSH in Japan. RESULTS: 25 women with BN received 16-20 sessions of face-to-face CBT-GSH. Primary outcomes were the completion rate of intervention and abstinence rates from objective bingeing and purging as assessed by the Eating Disorder Examination. Secondary outcomes were other self-report measurements of the frequency of bingeing and purging, and characteristic psychopathologies of eating disorders. Assessments were conducted before CBT as baseline as well as after CBT. 92% (23/25) of the participants completed the CBT sessions. After CBT-GSH, 40% (10/25) of the participants (intention-to-treat) achieved symptom abstinence. The mean binge and purge episodes during the previous 28 days improved from 21.88 to 10.96 (50% reduction) and from 22.44 to 10.88 (52% reduction), each (before CBT-GSH to after CBT-GSH), and the within-group effect sizes were medium (Cohen's d = 0.67, 0.65, each). Our study provided a preliminary evidence about the feasibility of CBT-GSH in Japanese clinical settings for the future. Trial registration This study was registered retrospectively in the national UMIN Clinical Trials Registry on July 10, 2013 (registration ID: UMIN000011120).
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Bulimia Nerviosa/terapia , Terapia Cognitivo-Conductual/métodos , Evaluación de Resultado en la Atención de Salud , Autocuidado/métodos , Adolescente , Adulto , Estudios de Factibilidad , Femenino , Humanos , Japón , Proyectos Piloto , Adulto JovenRESUMEN
Maxillary distraction is increasingly used for the correction of severe maxillary retrusion in patients with cleft lip and palate. However, control of the maxillary movement is difficult, and the need to wear visible distractors for a long period of time causes psychosocial problems. A two-stage surgical approach consisting of maxillary distraction and mandibular setback was developed to overcome these problems. In this study, changes in maxillofacial morphology and velopharyngeal function were examined in 22 patients with cleft lip and palate who underwent this two-stage approach. Lateral cephalograms taken just before the first surgery, immediately after the second surgery, and at completion of the active post-surgical orthodontic treatment were used to examine maxillofacial morphology. Velopharyngeal function was evaluated by speech therapists using a 4-point scale for hypernasality. The average forward movement of the maxilla with surgery at point A was 7.5mm, and the average mandibular setback at pogonion was 8.6mm. The average relapse rate during post-surgical orthodontic treatment was 25.2% for the maxilla and 11.2% for the mandible. After treatment, all patients had positive overjet, and skeletal relapse was covered by tooth movement during postoperative orthodontics. Velopharyngeal function was not changed by surgery. This method can shorten the period during which the distractors have to be worn and reduce the patient burden.
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Labio Leporino/cirugía , Fisura del Paladar/cirugía , Osteotomía Mandibular/métodos , Osteogénesis por Distracción/métodos , Insuficiencia Velofaríngea/cirugía , Adolescente , Adulto , Cefalometría , Labio Leporino/fisiopatología , Fisura del Paladar/fisiopatología , Femenino , Humanos , Masculino , Técnicas de Movimiento Dental , Resultado del Tratamiento , Insuficiencia Velofaríngea/fisiopatologíaRESUMEN
Serotype 23B Streptococcus pneumoniae was isolated from a 67-year-old Japanese patient with meningitis. This isolate was susceptible to penicillin G, while genotyped as gPISP with a mutation in a penicillin-binding motif in PBP2b. The 23B isolate was assigned to ST11996 that is related to CC439, a dominant group among serotype 23B.
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To understand a strong focusing phenomenon that occurs in a low-energy hydrogen ion beam, the electron temperature, the electron density, and the space potential in an ion source with cusped magnetic fields are measured before and after the transition to the focusing state using an electrostatic probe. The experimental results show that no significant changes are observed before or after the transition. However, we found unique phenomena that are characterized by the position of the electrostatic probe in the ion source chamber. Specifically, the extracted ion beam current density and energy are obviously enhanced in the case where the electrostatic probe, which is covered by a dielectric material, is placed close to an acceleration electrode.
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PURPOSE: Sirolimus (SRL) is used to treat pulmonary lymphangioleiomyomatosis (P-LAM). There is limited evidence that SRL has systemic efficacy for the patients with extrapulmonary lymphangioleiomyomatosis (E-LAM) remaining after lung transplantation (LT) for P-LAM. This report examines the efficacy of SRL treatment for the patient with E-LAM remaining after an LT for P-LAM. CASE SUMMARY: The course of the patient's recovery from an LT for P-LAM was complicated by lymphedema in the left femoral region that was caused by two E-LAM lesions remaining in the left pelvic cavity and in the retroperitoneal area. After the LT was performed, the patient started SRL treatment to reduce the E-LAM lesions. The daily SRL dose, selected based on the standard SRL dose for P-LAM, was initiated at 1 mg/d and was maintained at 2 mg/d. The remaining E-LAM lesions and lymphedema in the left femoral region improved in approximately 9 months after the LT with the administration of both SRL and the standard immunosuppressive therapy used by Okayama University Hospital, including tacrolimus, mycophenolate mofetil, and prednisolone. The SRL and tacrolimus trough concentrations in whole blood were maintained within the therapeutic window for the next 1.5 years after initiation of SRL treatment. The patient experienced no severe adverse events that required discontinuation of the SRL treatment during this time. CONCLUSION: The patients with remaining E-LAM lesions may receive SRL treatment to improve the quality of life after LT for P-LAM as effective therapy in cases where the patient's recovery is complicated by E-LAM lesions.
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Inmunosupresores/uso terapéutico , Neoplasias Pulmonares/tratamiento farmacológico , Trasplante de Pulmón , Linfangioleiomiomatosis/tratamiento farmacológico , Sirolimus/uso terapéutico , Abdomen/patología , Adulto , Femenino , Humanos , Terapia de Inmunosupresión/métodos , Neoplasias Pulmonares/patología , Linfangioleiomiomatosis/patología , Linfangioleiomiomatosis/cirugía , Linfedema/tratamiento farmacológico , Linfedema/etiología , Ácido Micofenólico/análogos & derivados , Ácido Micofenólico/uso terapéutico , Neoplasia Residual , Pelvis/patología , Prednisolona/uso terapéutico , Calidad de Vida , Tacrolimus/uso terapéuticoRESUMEN
AIMS: The results of previous randomised controlled trials suggest that radiation oncologists should consider the presence of neuropathic pain when they prescribe dose fractionations for painful bone metastases. Although validated screening tools for neuropathic pain features are currently available, the prevalence of such features among patients with painful bone metastases is still poorly understood. The purpose of this study was to estimate the prevalence of neuropathic pain features among patients who received palliative radiotherapy for painful bone metastases. MATERIALS AND METHODS: We conducted a cohort survey of consecutive patients who received palliative radiotherapy for painful bone metastases at St Luke's International Hospital between 2013 and 2014. Patients were prospectively assessed before radiotherapy using the validated screening questionnaire to identify neuropathic pain components in Japanese patients. Pain with neuropathic features was prospectively defined using the total score of the seven-item questionnaire and a cut-off score ≥9. The pain response was assessed 2 months after the start of radiotherapy according to the criteria defined by the International Bone Metastases Consensus Working Party. RESULTS: Eighty-seven patients were assessed. Twenty-four per cent of patients (95% confidence interval: 16-35%) were diagnosed as having pain with neuropathic features. On multivariate analysis, no significant correlations were seen between neuropathic pain features and patient characteristics. Sixty-four patients (74%) were assessable 2 months after the start of radiotherapy. Overall response rates were 59% (95% confidence interval: 33-82%) in patients with neuropathic features and 55% (95% confidence interval: 40-70%) in those without such features. CONCLUSIONS: A considerable proportion of the patients were proven to have bone pain with neuropathic features. Further investigations are warranted to validate symptom assessment tools in cooperation with pain distribution and image findings, and to clarify if the presence of neuropathic pain affects the response to palliative radiotherapy.
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Neoplasias Óseas/radioterapia , Fraccionamiento de la Dosis de Radiación , Neuralgia/diagnóstico , Radioterapia/efectos adversos , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias Óseas/secundario , Femenino , Humanos , Japón/epidemiología , Masculino , Persona de Mediana Edad , Neuralgia/etiología , Dimensión del Dolor , Cuidados Paliativos , Prevalencia , Estudios Prospectivos , Encuestas y CuestionariosRESUMEN
A high current density (≈3 mA/cm(2)) hydrogen ion beam source operating in an extremely low-energy region (E(ib) ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E(ib) is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.
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Proteínas del Citoesqueleto/genética , Neuropatía Axonal Gigante/genética , Neuropatía Axonal Gigante/patología , Disomía Uniparental/genética , Secuencia de Bases , Exoma/genética , Femenino , Homocigoto , Humanos , Imagen por Resonancia Magnética , Datos de Secuencia Molecular , Conducción Nerviosa/genética , Conducción Nerviosa/fisiología , Análisis de Secuencia de ADNRESUMEN
The self-focusing phenomenon has been observed in a high current density and low energy ion beam. In order to study the mechanism of this phenomenon, a special designed double probe to measure the electron density and temperature is installed into the chamber where the high current density ion beam is injected. Electron density profile is successfully measured without the influence of the ion beam components. Estimated electron temperature and density are â¼0.9 eV and â¼8 × 10(8) cm(-3) at the center of ion beam cross section, respectively. It was found that a large amount of electrons are spontaneously accumulated in the ion beam line in the case of self-forcing state.
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Spontaneous self-focusing of ion beam with high current density (Jc â¼ 2 mA/cm(2), Ib â¼ 65 mA) in low energy region (â¼150 eV) is observed in a hydrogen ion beam extracted from an ordinary bucket type ion source with three electrodes having concave shape (acceleration, deceleration, and grounded electrodes). The focusing appears abruptly in the beam energy region over â¼135-150 eV, and the Jc jumps up from 0.7 to 2 mA/cm(2). Simultaneously a strong electron flow also appears in the beam region. The electron flow has almost the same current density. Probably these electrons compensate the ion space charge and suppress the beam divergence.