Laser-assisted Simulation of Dose Rate Effects of Wide Band Gap Semiconductor Devices

Laser-assisted simulation technique has played a crucial role in the investigation of dose rate effects of silicon-based devices and integrated circuits,due to its exceptional advantages in terms of flexibility,safety,convenience,and precision.In recent years,wide band gap materials,known for their strong bonding and high ionization energy,have gained increasing attention from researchers and hold significant promise for extensive applications in specialized environments.Consequently,there is a growing need for comprehensive research on the dose rate effects of wide band gap materials.In response to this need,the use of laser-assisted simulation technology has emerged as a promising approach,offering an effective means to assess the efficacy of investigating these materials and devices.This paper focused on investigating the feasibility of laser-assisted simulation to study the dose rate effects of wide band gap semiconductor devices.Theoretical conversion factors for laser-assisted simulation of dose rate effects of GaN-based and SiC-based devices were been provided.Moreover,to validate the accuracy of the conversion factors,pulsed laser and dose rate experiments were conducted on GaN-based and SiC-based PIN diodes.The results demonstrate that pulsed laser radiation andγ-ray radiation can produce highly similar photocurrent responses in GaN-based and SiC-based PIN diodes,with correlation coefficients of 0.98 and 0.974,respectively.This finding reaffirms the effectiveness of laser-assisted simulation technology,making it a valuable complement in studying the dose rate effects of wide band gap semiconductor devices.

Public Effective Dose Assessment Using Gross Alpha and Beta Radioactivity Levels of Tap Drinking Water in the District of Abidjan, Cote d’Ivoire

In order to assess public effective dose due to gross alpha and beta in water, 43 tap water samples were collected from different areas in the District of Abidjan. Using the low background Gas-less Automatic Alpha/Beta counting system (Canberra iMaticTM) for analysis, the gross alpha and beta concentrations found varied from 0.001 ± 0.002 to 0.063 ± 0.050 Bq/l with an average of 0.013 ± 0.012 Bq/l and from 0.067 ± 0.080 to 0.320 ± 0.120 Bq/l with an average of 0.174 ± 0.076 Bq/l, respectively in samples. The public effective dose assessment showed values of dose to ingestion of alpha and beta emitter radionuclides lower than the recommended value of dose for drinking water 0.1 mSv/y, except in 30% of the samples. These results show the need for additional studies to be conducted in order to clarify the hazardousness of these water samples. However, this study still remains important because it has provided necessary data for future tap water quality monitoring studies in the District of Abidjan.

Effectiveness of COVID-19 Vaccine Doses in Children: Case of Lake Region Economic Bloc-Kenya

Introduction: Vaccination of children has experienced delays due to paucity of information regarding safety, effectiveness, immunogenicity, and reactogenicity. Age wise approval prioritized 12 - 17 years and later 5 - 11 years. Those below 5 years possess na?ve immunity and not considered. In Lake Region Economic Bloc children aged 12 - 17 variably received 1, 2, and 3 doses of vaccine. This analysis looks into effectiveness of the doses administered. Method: Data providers from 84 LREB facilities submitted patients’ vaccination data to Power BI supported dashboard between June 24, 2021 and July 30, 2022. Data of 12 - 17 years old was mined, analyzed and visualized. Sample sizes considered for analysis were 0 dose, n = 8132;1 dose, n = 271;2 doses, n = 402, and 3 doses, n = 90. Data used in the analysis was facility operational and not from experimental design. Relative risk analysis of children who received 0, 1, 2, and 3 doses was done using Odds Ratio run on R software. Results: The relative risk of infection to a child with one dose against unvaccinated counterpart is 0.92 (95% CI, 0.61 - 1.43). Likewise the relative risk of infection to a child aged 12 - 17 years with 2 doses against another who received no dose is 0.87 (95% CI, 0.63 - 1.24). A child with 3 doses is 46% (95% CI, 27% - 84%) less likely to get infected compared to another not vaccinated. Also, the relative risk between having 2 doses and 1 dose for a child aged 12 - 17 years is 0.95 (95% CI, 0.55 - 1.6). For the same age group the relative risk of having 3 doses of vaccines against 1 dose is 51% (95% CI, 26% - 100%). In addition, a child who receives 3 doses of vaccine is 53% (95% CI, 28% - 100%) less likely to experience breakthrough infection compared to another with 2 doses. Whereas 1st dose offers (5%) marginal protection advantage over the 2nd dose, the 3r dose offers 49% and 47% more protection over 1st and 2nd doses, respectively, because of incremental reduced risk of infection gained from previous doses. During the period, 15 children at risk were admitted with COVID-19 infections in various regional hospitals, one had 3 doses but confounded with severe comorbidity. Conclusion: We found that 2nd dose had marginal protection over the 1st dose. However, the 3rd dose offers extensive protection compared to 1st and 2nd doses, and protects more against hospitalization. Children at risk should receive 3 doses of vaccines.

Review on Hydroxyurea Usage in Young Children with Sickle Cell Disease: Examining Hemoglobin Induction, Potential Benefits, Responses, Safety, and Effectiveness

Sickle cell disease (SCD) is a prevalent condition, particularly in the countries of sub-Saharan Africa, where the presence of specific genes associated with Malaria contributes to its high prevalence. Patients with sickle cell disease frequently experience painful episodes necessitating hospitalization, and their hemoglobin levels are typically lower than those of the general population. There are different treatment options available to manage complications, such as transfusing blood, hydroxyurea, and strong anti-pains. However, with all these treatments, patients still commonly experience pain crises and suffer from organ damage. Hydroxyurea, the sole approved medication for sickle cell anemia in developed and developing countries, is widely used in children despite being primarily indicated for adults. Multiple studies have demonstrated the efficacy of hydroxyurea in inducing HbF production in young children with SCD. Elevated HbF levels have been associated with improved clinical outcomes, including a reduction in vaso-occlusive crises, acute chest syndrome, and the need for blood transfusions. Furthermore, increased HbF levels have been shown to ameliorate disease-related organ damage, such as pulmonary hypertension and sickle cell retinopathy. The response to hydroxyurea treatment in young children with SCD is variable. Some patients achieve substantial increases in HbF levels and experience significant clinical benefits, while others may have a more modest response. Factors influencing the response include baseline HbF levels, genetic modifiers, treatment adherence, and dose optimization. Safety is a crucial consideration when using hydroxyurea in young children. Studies have shown that hydroxyurea is generally well-tolerated, with the most common adverse effects being myelosuppression, gastrointestinal symptoms, and dermatological manifestations. However,long-term effects and potential risks, such as renal dysfunction and reproductive impacts, require further investigation. The effectiveness of hydroxyurea in young children with SCD has been demonstrated in various clinical trials and observational studies. These studies have shown a significant reduction in disease-related complications and improved quality of life. However, optimal dosing, treatment duration, and long-term outcomes are still areas of ongoing research. This review focuses on recent studies investigating the benefits, effectiveness, responses, and safety of hydroxyurea in pediatric individuals diagnosed with sickle cell disease.

Machine learning-based analyses for total ionizing dose effects in bipolar junction transistors

Machine learning methods have proven to be powerful in various research fields.In this paper,we show that research on radiation effects could benefit from such methods and present a machine learning-based scientific discovery approach.The total ionizing dose(TID)effects usually cause gain degradation of bipolar junction transistors(BJTs),leading to functional failures of bipolar integrated circuits.Currently,many experiments of TID effects on BJTs have been conducted at different laboratories worldwide,producing a large amount of experimental data which provides a wealth of information.However,it is difficult to utilize these data effectively.In this study,we proposed a new artificial neural network(ANN)approach to analyze the experimental data of TID effects on BJTs An ANN model was built and trained using data collected from different experiments.The results indicate that the proposed ANN model has advantages in capturing nonlinear correlations and predicting the data.The trained ANN model suggests that the TID hardness of a BJT tends to increase with base current I.A possible cause for this finding was analyzed and confirmed through irradiation experiments.

Total ionizing dose and synergistic effects of magnetoresistive random-access memory

A magnetoresistive random-access memory(MRAM) device was irradiated by ^(60) Co c-rays and an electron beam.The synergistic effect of this on the MRAM was tested with an additional magnetic field during irradiation,from which the total ionizing dose(TID) and the synergistic damage mechanism of MRAM were analyzed.In addition,DC,AC,and functional parameters of the memory were tested under irradiation and annealing via a very large-scale integrated circuit test system.The radiation-sensitive parameters were obtained through analyzing the data.Because of the magnetic field applied on the MRAM while testing the synergistic effects,shallow trench isolation leakage and Frenkel–Poole emission due to synergistic effects were smaller than that of TID,and hence radiation damage of the synergistic effects was also lower.

Suppressing the hot carrier injection degradation rate in total ionizing dose effect hardened nMOSFETs

Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose （TID） effect. However, their capability of resisting the hot carrier effect （HCE） has also been proven to be very weak. In this paper, the reason why the annular gate nMOSFETs have good TID but bad HCE resistance is discussed in detail, and an improved design to locate the source contacts only along one side of the annular gate is used to weaken the HCE degradation. The good TID and HCE hardened capability of the design are verified by the experiments for I/O and core nMOSFETs in a 0.18 μm bulk CMOS technology. In addition, the shortcoming of this design is also discussed and the TID and the HCE characteristics of the replacers （the annular source nMOSFETs） are also studied to provide a possible alternative for the designers.

Dose Effects of Ion Beam Exposure on Deinococcus Radiodurans: Survival and Dose Response

To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.coli, as the control) for ultra-violet (UV), γ-rays radiation and ion beam exposure was investigated. The shoulder type of survival curves were found for both UV and γ-ray ionizing radiation, but the saddle type of survival curves were shown for H+、 N+( 20keV and 30keV) and Ar+ beam exposure. This dose effect of the survival initially decreased with the increase in dose and then increased in the high dose range and finally decreased again in the higher dose range. Our experimental results suggest that D. radiodurans, which is considerably radio-resistant to UV and x-ray and γ-ray ionizing radiation, do not resist ion beam exposure.

Effects of total dose irradiation on the threshold voltage of H-gate SOI NMOS devices

This work researched the impact of total dose irradiation on the threshold voltage of N-type metal oxide semiconductor field effect transistors(nMOSFETs) in silicon-on-insulator(SOI) technology.Using the subthreshold separation technology,the factor causing the threshold voltage shift was divided into two parts:trapped oxide charges and interface states,the effects of which are presented under irradiation.Furthermore,by analyzing the data,the threshold voltage shows a negative shift at first and then turns to positive shift when irradiation dose is lower.Additionally,the influence of the dose rate effects on threshold voltage is discussed.The research results show that the threshold voltage shift is more significant in low dose rate conditions,even for a low dose of100 krad(Si).The degeneration value of threshold voltage is 23.4%and 58.0%for the front-gate and the back-gate at the low dose rate,respectively.

Total Ionization Dose Effects on Charge Storage Capability of Al2O3/HfO2/Al2O3-Based Charge Trapping Memory Cell

Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/Al2O3（AHA） high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage（V（fb））. The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.

Dose-effect correlation of chloride de-icing salt on Euonymus japonicus

In order to prevent severe pollution by de-icing salt on greenery along urban roads, a half lethal dose （LD_50）for a plant population was confirmed through stress simulation of chloride de-icing salt on Euonymus japonicus, with an ianalysis of physiological changes, statistics on mortality rate on plant populations and mathematic modeling during a 30- day subacute toxicity test. The results indicate that a significant positive correlation in the early stages and a significant negative correlation in the later stages were observed between the amount of chlorophyll a and b in plants and a cumulative dose of de-icing salt. The amounts of free proline in plants and the dose of de-icing salt were positively correlated Over the entire period. No significant correlation in the initial stage, but a significant negative correlation in later stages was observed between the soluble protein and the dose of de-icing salt. LDs0 of this chloride agent on E. japonicus is 5 kg.（L·m2）-1 over 30 days.

How to conduct an acupuncture dose–effect relationship study? A discussion based on study methodology

Acupuncture therapy is widely used in the clinic,and its therapeutic effects have been proven by numerous studies.The dose–effect relationship of acupuncture is a fundamental aspect of the acupuncture research system.Recent studies found that different acupuncture dosages altered study results directly,indicating the importance of screening the optimal stimulation dosage.However,the system for studying the acupuncture dose–effect relationship is still in its infancy,and the methodology of the system needs to be improved.This review aimed to define the factors impacting acupuncture“dosage”and“effect,”and to improve the methodological system for research on the dose–effect relationship of acupuncture.By summarizing the current findings of acupuncture dose–effect studies,we discussed the vital acupuncture parameters and methodological problems that influence the relationship between acupuncture dosage and its effects.These factors consist of specific influencing factors(acupoint selection,acupuncture manipulation parameters,de qi response)and nonspecific influencing factors(comparison selection,blinding procedure,patient expectancy).Our perspectives offer suggestions for the design of acupuncture dosage–effect trials.Further studies need to be conducted to establish the methodological system and provide systematic evidence of the acupuncture dose–effect relationship.

Effect of Low Dose Radiation on Intracellular Calcium and Protein Kinase C in Lymphocytes

It is first reported in the present paper that whole-body irradiation (WBI) with low dose X-rays could increase intracellular calcium ions ([Ca2+]i) and stimulate protein kinase C (PKC) activity of mouse lymphocytes. Following WBI of male Kunming micc With 75 mGy X-rays at a dose rate of 12.5 mGy/min the mobilization of [Ca2+]i with Con A in CD4+ and CD8+ Cells in the thymus and spleen was potentiated and the amplitude of [Ca2+], mobilization in thymocytes in response to anti-CD3 monoclonal antibody increased with time from 4 to 24 h following low dose radiation. The PKC activity in the homogenate of spleen was markedly stimulated 12 h after WBl with 75 mGy, reaching its peak value at 24-48 h and coming down to lower than normal on day 7. However, the PKC activity in the separated T lymphocytes reached its peak value at 12 h and that in the B lymphocytes reached its peak value on day 4, both coming down to below control on day 7. The implications of this facilitation of signal transduction in T lymphocytes in the mechanism of immunoenhancement after low dose radiation were discussed

Hot-Carrier Effects on Total Dose Irradiated 65 nm n-Type Metal-Oxide-Semiconductor Field-Effect Transistors

The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation （STI）. The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.

Dose-dependent effects of NMDA on retinal and optic nerve morphology in rats

AIM: To investigate dose-dependent effects of N-methylD-aspartate(NMDA) on retinal and optic nerve morphology in rats.METHODS: Sprague Dawley rats, 180-250 g in weight were divided into four groups. Groups 1, 2, 3 and 4 were intravitreally administered with vehicle and NMDA at the doses 80, 160 and 320 nmol respectively. Seven days after injection, rats were euthanized, and their eyes were taken for optic nerve toluidine blue and retinal hematoxylin and eosin stainings. The TUNEL assay was done for detecting apoptotic cells.RESULTS: All groups treated with NMDA showed significantly reduced ganglion cell layer(GCL) thickness within inner retina, as compared to control group. Group NMDA 160 nmol showed a significantly greater GCL thickness than the group NMDA 320 nmol. Administration of NMDA also resulted in a dose-dependent decrease in the number of nuclei both per 100 μm GCL length and per 100 μm2 of GCL. Intravitreal NMDA injection caused dosedependent damage to the optic nerve. The degeneration of nerve fibres with increased clearing of cytoplasm was observed more prominently as the NMDA dose increased. In accordance with the results of retinal morphometry analysis and optic nerve grading, TUNEL staining demonstrated NMDA-induced excitotoxic retinal injury in a dose-dependent manner.CONCLUSION: Our results demonstrate dose-dependent effects of NMDA on retinal and optic nerve morphology in rats that may be attributed to differences in the severity of excitotoxicity and oxidative stress. Our results also suggest that care should be taken while making dose selections experimentally so that the choice might best uphold study objectives.

Effective Dose Levels from Computed Tomography of the Head during Contrast Studies in Nigeria

Background: Diagnostic reference levels for a number of common diagnostic radiological examinations against which individual centres could compare their performance have been recommended by relevant international agencies. Due to variations in different populations globally, local and national diagnostic reference levels are more reliable. To the best of our knowledge, no centre-specific study has been carried out and national surveys are not available. Objective: To establish a preliminary local and national diagnostic reference level in Nigeria. Methods: A pro-spective and cross-sectional study involving 30 conscious paediatrics and adult patients referred for head computed tomography scan. They were positioned supine and scanned according to the standard protocol for head computed tomography with manual mA selection. The total dose-length products were recorded at the end of the pre-contrast and post-contrast sequences respectively. The pre-contrast dose was taken into cognizance in the determination of the post-contrast value. The effective dose was established by multiplying the dose-length product by 0.0023 mSv.mGy-1.cm-1, a conversion coefficient for brain tissue adopted from the European Commission. Statistical Package for Social Sciences version 17.0 was used to analyze the data. Results: 30 paediatrics and adult patients of mixed gender participated in the study. Their ages ranged from 1 to 74 years with a mean age of 41.47 ± 23.30 years. The pre-contrast effective dose ranged from 1.93 mSv to 3.32 mSv with mean of 2.56 ± 0.51 mSv and 75th percentile of 3.11 mSv while the post-contrast effective dose ranged from 4.06 mSv to 6.97 mSv with mean of 5.27 ± 0.97 mSv and 75th percentile of 6.13 mSv. The mean effective dose from this work and two other isolated studies was 3.0 mSv. Conclusion: Although our quantified doses are below threshold limits for occupational exposures they are higher than the recommended level for the public. A further optimization of scanning protocols by the radiographers could lower the effective dose for patients undergoing contrast head computed tomography in our centre and in the country.

Research on total-dose irradiation effect of hardened partially-depleted NMOSFET/SIMOX

In this work, top and back gate characteristics of partially-depleted NMOS transistors with enclosed gate fabricated on SIMOX which is hardened by silicon ions implantation were studied under X-ray total-dose irradiation of three bias conditions. It has been found experimentally that back gate threshold shift and leakage current were greatly reduced during irradiation for hardened transistors, comparing to control ones. It has been confirmed that the improvement of total-dose properties of SOI devices is attributed to the silicon nanocrystals (nanoclusters) in buried oxides introduced by ion implantation.

Study of total ionizing dose radiation effects on enclosed gate transistors in a commercial CMOS technology

This paper studies the total ionizing dose radiation effects on MOS （metal-oxide-semiconductor） transistors with normal and enclosed gate layout in a standard commercial CMOS （compensate MOS） bulk process. The leakage current, threshold voltage shift, and transconductance of the devices were monitored before and after γ-ray irradiation. The parameters of the devices with different layout under different bias condition during irradiation at different total dose are investigated. The results show that the enclosed layout not only effectively eliminates the leakage but also improves the performance of threshold voltage and transconductance for NMOS （n-type channel MOS） transistors. The experimental results also indicate that analogue bias during irradiation is the worst case for enclosed gate NMOS. There is no evident different behaviour observed between normal PMOS （p-type channel MOS） transistors and enclosed gate PMOS transistors.

Estimation of Annual Effective Dose Due to Ingestion of Natural Radionuclides in Cattle in Tin Mining Area of Jos Plateau, Nigeria

Contamination of land could occur during the extraction and handling of materials containing high levels of naturally occurring radionuclide materials. These radionuclides find their ways into the food chain. The activity concentrations of natural radionuclides 40K, 226Ra, and 232Th in heart, liver, kidney, lungs, spleen and beef of cattle slaughtered and consumed in a tin mining area of Jos Plateau, Nigeria were determined by gamma ray spectroscopy method. The activity concentration of 40K is the highest in all the samples. The annual effective dose to man through the ingestion of the radionuclides in the organs was estimated. The mean annual effective doses calculated are 35.35 ± 13.84, 57.89 ± 38.27 and 46.93 ± 10.28 μSv?y?1 for heart, liver and kidney, respectively. Those of lungs, spleen and meat are 28.44 ± 15.70, 48.34 ± 28.85 and 41.24 ± 3.56 μSv?y?1, respectively. These are of the order of two magnitudes higher than those obtained for food in Abeokuta, Nigeria.

Measurement of Electron Return Effect and Skin Dose Reduction by a Bolus in an Anthropomorphic Physical Phantom under a Magnetic Resonance Guided Linear Accelerator (MR-LINAC) System

Background: Magnetic resonance image-guided radiation therapy (MR-IGRT) promises more precise and effective radiation treatments compared to conventional IGRT by using real-time on-board MR imaging. Under the influence of a magnetic field, however, secondary electrons exiting a surface can be forced in a circular path and re-enter the medium, resulting in dose increase at a beam-exit surface, called the electron return effect (ERE). The purpose of the study is to compare the exit skin dose computed by Monte Carlo dose calculation with measurements using an adult anthropomorphic phantom and to measure the effect of skin dose reduction by adding 1 cm-thick bolus. Method: The plan was compared with measurements using an adult anthropomorphic phantom combined with radiochromic films and thermoluminescent dosimeters. We also measured the skin dose reduction by adding 1 cm-thick bolus on the frontal surface of the phantom. Results: We found that 1 cm-thick bolus reduced the skin dose by up to 20% both in measurements and calculations. The plan was found to overestimate the measured skin dose by about 10% and there was no significant difference in the bolus effect between the breast skin and the skin (without breast attachment) doses. Conclusion: In conclusion, we confirmed the ERE effect on the anthropomorphic phantom under the magnetic field and the exit skin dose reduction by adding a bolus. Skin dose measurements using anthropomorphic phantom may be helpful to evaluate more realistic skin dose and the bolus effect in the magnetic field.