Assessment of Occupational Radiation Exposure for Radiotherapy Healthcare Workers at Kenyatta National Hospital Using Thermoluminescence Dosimeter LiF:Mg,Ti

Kenyatta National Hospital (KNH) is the largest public referral hospital with a comprehensive cancer treatment facility in East and Central Africa. Occupational radiation monitoring is a significant technique for demonstrating compliance of radiation regulatory limits. The objective of the study was to carry out assessment of occupational radiation exposure among radiotherapy personnel at KNH using thermoluminescence dosimeter, TLD. KNH staff were monitored using dosimeter type TLD-100 made of LiF:Mg,Ti, on monthly basis. The reader system used for analysis was Harshaw 8800. The measurement established the average monthly accumulated occupational personnel dose for KNH to be 0.21 mSv and 0.29 mSv for Hp (10) and Hp (0.07) respectively. The accumulated dose results were within the maximum acceptable dose of 1.67 mSv/month and 41.6 mSv/month for Hp (10) and Hp (0.07) respectively. The investigation results were higher than the acceptable public limit of 0.08 mSv/month. Moreover, incidences were noted where the fetus dose limit 0.42 was also exceeded. Evaluation of statistical dose exposure among doctors, nurses and radiographers’ measurement results were within ±0.02 mSv. The study established the average KNH occupational radiation exposure levels for both Hp (10) and Hp (0.07) were within the ICRU recommendation, validating radiation protection safe practice. Data analysis of healthcare workers did not indicate exposure trend biased to any healthcare profession. Hence radiation risk cut across all professional categories. It is recommended that Radiation Monitoring program be reviewed to include non-clinical staff who access the facility. Radiation reporting should not be limited to one facility, but reflect cases where workers are involved in multiple multiple jobs.

Unraveling the efficacy network: A network meta-analysis of adjuvant external beam radiation therapy methods after hepatectomy

BACKGROUND Primary liver cancer is a malignant tumor with a high recurrence rate that significantly affects patient prognosis.Postoperative adjuvant external radiation therapy(RT)has been shown to effectively prevent recurrence after liver cancer resection.However,there are multiple RT techniques available,and the differ-ential effects of these techniques in preventing postoperative liver cancer re-currence require further investigation.AIM To assess the advantages and disadvantages of various adjuvant external RT methods after liver resection based on overall survival(OS)and disease-free survival(DFS)and to determine the optimal strategy.METHODS This study involved network meta-analyses and followed the PRISMA guidelines.The data of qualified studies published before July 10,2023,were collected from PubMed,Embase,the Web of Science,and the Cochrane Library.We included relevant studies on postoperative external beam RT after liver resection that had OS and DFS as the primary endpoints.The magnitudes of the effects were determined using risk ratios with 95%confidential intervals.The results were analyzed using R software and STATA software.RESULTS A total of 12 studies,including 1265 patients with hepatocellular carcinoma(HCC)after liver resection,were included in this study.There was no significant heterogeneity in the direct paired comparisons,and there were no significant differences in the inclusion or exclusion criteria,intervention measures,or outcome indicators,meeting the assumptions of heterogeneity and transitivity.OS analysis revealed that patients who underwent stereotactic body radiotherapy(SBRT)after resection had longer OS than those who underwent intensity modulated radiotherapy(IMRT)or 3-dimensional conformal RT(3D-CRT).DFS analysis revealed that patients who underwent 3D-CRT after resection had the longest DFS.Patients who underwent IMRT after resection had longer OS than those who underwent 3D-CRT and longer DFS than those who underwent SBRT.CONCLUSION HCC patients who undergo liver cancer resection must consider distinct advantages and disadvantages when choosing between SBRT and 3D-CRT.IMRT,a RT technique that is associated with longer OS than 3D-CRT and longer DFS than SBRT,may be a preferred option.

Selective internal radiation therapy segmentectomy:A new minimally invasive curative option for primary liver malignancies?

Transarterial radioembolization or selective internal radiation therapy(SIRT)has emerged as a minimally invasive approach for the treatment of tumors.This percutaneous technique involves the local,intra-arterial delivery of radioactive microspheres directly into the tumor.Historically employed as a palliative measure for liver malignancies,SIRT has gained traction over the past decade as a potential curative option,mirroring the increasing role of radiation segmentectomy.The latest update of the BCLC hepatocellular carcinoma guidelines recognizes SIRT as an effective treatment modality comparable to other local ablative methods,particularly well-suited for patients where surgical resection or ablation is not feasible.Radiation segmentectomy is a more selective approach,aiming to deliver high-dose radiation to one to three specific hepatic segments,while minimizing damage to surrounding healthy tissue.Future research efforts in radiation segmentectomy should prioritize optimizing radiation dosimetry and refining the technique for super-selective administration of radiospheres within the designated hepatic segments.

Fifteen years of preclinical and clinical experiences about biotherapy treatment of lesions induced by accidental irradiation and radiotherapy

High dose radiation exposures involving medical treatments or accidental irradiation may lead to extended damage to the irradiated tissue. Alleviation or even eradication of irradiation induced adverse events is therefore crucial. Because developments in cell therapy have brought some hope for the treatment of tissues damages induced by irradiation, the Institute for Radiation and Nuclear Safety contributed to establish the clinical guidelines for the management of accidentally irradiated victims and to provide the best supportive care to patients all over the world. In the past 15 years, we contributed to develop and test cell therapy for protection against radiation side effects in several animalmodels, and we proposed mechanisms to explain the benefit brought by this new therapeutic approach. We established the proof of concept that mesenchymal stem cells (MSCs) migrate to damaged tissues in the nonobese diabetic/severe combined immunodeficiency immunotolerant mice model and in non-human primate after radiation exposure. We showed that the intravenous injection of MSCs sustains hematopoiesis after total body irradiation, improves wound healing after radiodermatitis and protects gut function from irradiation damages. Thanks to a tight collaboration with clinicians from several French hospitals, we report successful treatments of therapeutic/accidental radiation damages in several victims with MSC infusions for hematopoiesis correction, radio-induced burns, gastrointestinal disorders and protection homeostatic functions of gut management after radio-therapy.

Establishment of a prediction model for severe acute radiation enteritis associated with cervical cancer radiotherapy

BACKGROUND Cervical cancer is one of the most common gynecological malignant tumors.Radiation enteritis(RE)leads to radiotherapy intolerance or termination of radiotherapy,which negatively impacts the therapeutic effect and seriously affects the quality of life of patients.If the incidence of RE in patients can be predicted in advance,and targeted clinical preventive treatment can be carried out,the side effects of radiotherapy in cervical cancer patients can be significantly reduced.Furthermore,accurate prediction of RE is essential for the selection of individualized radiation dose and the optimization of the radiotherapy plan.AIM To analyze the relationships between severe acute RE(SARE)of cervical cancer radiotherapy and clinical factors and dose-volume parameters retrospectively.METHODS We included 50 cervical cancer patients who received volumetric modulated arc therapy(VMAT)from September 2017 to June 2018 in the Department of Radiotherapy at The First Affiliated Hospital Soochow University.Clinical and dose-volume histogram factors of patients were collected.Logistic regression analysis was used to evaluate the predictive value of each factor for SARE.A nomogram to predict SARE was developed(SARE scoring system≥3 points)based on the multiple regression coefficients;validity was verified by an internal verification method.RESULTS Gastrointestinal and hematological toxicity of cervical cancer VMAT gradually increased with radiotherapy and reached the peak at the end of radiotherapy.The main adverse reactions were diarrhea,abdominal pain,colitis,anal swelling,and blood in the stool.There was no significant difference in the incidence of gastrointestinal toxicity between the radical and postoperative adjuvant radiotherapy groups(P>0.05).There were significant differences in the small intestine V_(20),V_(30),V_(40),and rectal V40 between adjuvant radiotherapy and radical radiotherapy after surgery(P<0.05).Univariate and multivariate analyses revealed anal bulge rating(OR:14.779,95%CI:1.281-170.547,P=0.031)and disease activity index(DAI)score(OR:53.928,95%CI:3.822-760.948,P=0.003)as independent predictors of SARE.CONCLUSION Anal bulge rating(>0.500 grade)and DAI score(>2.165 points)can predict SARE.The nomogram shows potential value in clinical practice.

Failure mechanism and infrared radiation characteristic of hard siltstone induced by stratification effect

The deformation in sedimentary rock induced by train loads has potential threat to the safe operation of tunnels. This study investigated the influence of stratification structure on the infrared radiation and temporal damage mechanism of hard siltstone. The uniaxial compression tests, coupled with acoustic emission(AE) and infrared radiation temperature(IRT) were conducted on siltstones with different stratification effects. The results revealed that the stratigraphic structure significantly affects the stress-strain response and strength degradation characteristics. The mechanical parameters exhibit anisotropy characteristics, and the stratification effect exhibits a negative correlation with the cracking stress and peak stress. The failure modes caused by the stratification effect show remarkable anisotropic features, including splitting failure(Ⅰ: 0°-22.50°, Ⅱ: 90°), composite failure(45°), and shearing failure(67.50°). The AE temporal sequences demonstrate a stepwise response characteristic to the loading stress level. The AE intensity indicates that the stress sensitivity of shearing failure and composite failure is generally greater than that of splitting failure. The IRT field has spatiotemporal migration and progressive dissimilation with stress loading and its dissimilation degree increases under higher stress levels. The stronger the stratification effect, the greater the dissimilation degree of the IRT field. The abnormal characteristic points of average infrared radiation temperature(AIRT) variance at local stress drop and peak stress can be used as early and late precursors to identify fracture instability. Theoretical analysis shows that the competitive relationship between compaction strengthening and fracturing damage intensifies the dissimilation of the infrared thermal field for an increasing stress level. The present study provides a theoretical reference for disaster warnings in hard sedimentary rock mass.

Wharton’s jelly mesenchymal stem cells: Future regenerative medicine for clinical applications in mitigation of radiation injury

Wharton’s jelly mesenchymal stem cells(WJ-MSCs)are gaining significant attention in regenerative medicine for their potential to treat degenerative diseases and mitigate radiation injuries.WJ-MSCs are more naïve and have a better safety profile,making them suitable for both autologous and allogeneic transplantations.This review highlights the regenerative potential of WJ-MSCs and their clinical applications in mitigating various types of radiation injuries.In this review,we will also describe why WJ-MSCs will become one of the most probable stem cells for future regenerative medicine along with a balanced view on their strengths and weaknesses.Finally,the most updated literature related to both preclinical and clinical usage of WJ-MSCs for their potential application in the regeneration of tissues and organs will also be compiled.

Simulation of the Ecosystem Productivity Responses to Aerosol Diffuse Radiation Fertilization Effects over the Pan-Arctic during 2001–19

The pan-Arctic is confronted with air pollution transported from lower latitudes.Observations have shown that aerosols help increase plant photosynthesis through the diffuse radiation fertilization effects(DRFEs).While such DRFEs have been explored at low to middle latitudes,the aerosol impacts on pan-Arctic ecosystems and the contributions by anthropogenic and natural emission sources remain less quantified.Here,we perform regional simulations at 0.2o×0.2ousing a well-validated vegetation model(Yale Interactive terrestrial Biosphere,YIBs)in combination with multi-source of observations to quantify the impacts of aerosol DRFEs on the net primary productivity(NPP)in the pan-Arctic during 2001-19.Results show that aerosol DRFEs increase pan-Arctic NPP by 2.19 Pg C(12.8%)yr^(-1)under clear-sky conditions,in which natural and anthropogenic sources contribute to 8.9% and 3.9%,respectively.Under all-sky conditions,such DRFEs are largely dampened by cloud to only 0.26 Pg C(1.24%)yr^(-1),with contributions of 0.65% by natural and 0.59% by anthropogenic species.Natural aerosols cause a positive NPP trend of 0.022% yr^(-1)following the increased fire activities in the pan-Arctic.In contrast,anthropogenic aerosols induce a negative trend of-0.01% yr^(-1)due to reduced emissions from the middle latitudes.Such trends in aerosol DRFEs show a turning point in the year of 2007 with more positive NPP trends by natural aerosols but negative NPP trends by anthropogenic aerosols thereafter.Though affected by modeling uncertainties,this study suggests a likely increasing impact of aerosols on terrestrial ecosystems in the pan-Arctic under global warming.

Magnetic resonance imaging for prostate cancer before radical and salvage radiotherapy: What radiation oncologists need to know

External beam radiotherapy(EBRT) is one of the principal curative treatments for patients with prostate cancer(PCa). Risk group classification is based on prostate-specific antigen(PSA) level, Gleason score, and T-stage. After risk group determination, the treatment volume and dose are defined and androgen deprivation therapy is prescribed, if appropriate. Traditionally, imaging has played only a minor role in T-staging due to the low diagnostic accuracy of conventional imaging strategies such as transrectal ultrasound, computed tomography, and morphologic magnetic resonance imaging(MRI). As a result, a notable percentage of tumours are understaged, leading to inappropriate and imprecise EBRT. The development of multiparametric MRI(mp MRI), an imaging technique that combines morphologic studies with functional diffusion-weighted sequences and dynamic contrastenhanced imaging, has revolutionized the diagnosis and management of PCa. As a result, mpM RI is now used in staging PCa prior to EBRT, with possible implications for both risk group classification and treatment decisionmaking for EBRT. mpM RI is also being used in salvageradiotherapy(SRT), the treatment of choice for patients who develop biochemical recurrence after radical prostatectomy. In the clinical context of biochemical relapse, it is essential to accurately determine the site of recurrence-pelvic(local, nodal, or bone) or distant-in order to select the optimal therapeutic management approach. Studies have demonstrated the value of mpM RI in detecting local recurrences-even in patients with low PSA levels(0.3-0.5 ng/m L)-and in diagnosing bone and nodal metastasis. The main objective of this review is to update the role of mpM RI prior to radical EBRT or SRT. We also consider future directions for the use and development of MRI in the field of radiation oncology.

A model to predict the risk of lethal nasopharyngeal necrosis after re-irradiation with intensity-modulated radiotherapy in nasopharyngeal carcinoma patients

Background:For patients with nasopharyngeal carcinoma(NPC) who undergo re-irradiation with intensity-modulated radiotherapy(IMRT),lethal nasopharyngeal necrosis(LNN) is a severe late adverse event.The purpose of this study was to identify risk factors for LNN and develop a model to predict LNN after radical re-irradiation with IMRT in patients with recurrent NPC.Methods:Patients who underwent radical re-irradiation with IMRT for locally recurrent NPC between March 2001 and December 2011 and who had no evidence of distant metastasis were included in this study.Clinical characteristics,including recurrent carcinoma conditions and dosimetric features,were evaluated as candidate risk factors for LNN.Logistic regression analysis was used to identify independent risk factors and construct the predictive scoring model.Results:Among 228 patients enrolled in this study,204 were at risk of developing LNN based on risk analysis.Of the 204 patients treated,31(15.2%) developed LNN.Logistic regression analysis showed that female sex(P = 0.008),necrosis before re-irradiation(P = 0.008),accumulated total prescription dose to the gross tumor volume(GTV) ≥ 145.5 Gy(P = 0.043),and recurrent tumor volume >25.38 cm3(P = 0.009) were independent risk factors for LNN.A model to predict LNN was then constructed that included these four independent risk factors.Conclusions:A model that includes sex,necrosis before re-irradiation,accumulated total prescription dose to GTV,and recurrent tumor volume can effectively predict the risk of developing LNN in NPC patients who undergo radical re-irradiation with IMRT.

Dosimetric Comparison of Integral Radiation Dose: Anisotropic Analytical Algorithm and Acuros XB in Breast Radiotherapy

The impact of the difference between Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) in breast radiotherapy is not clearly due to different uses and further research is required to explain this effect. The aim of this study is to investigate the contribution of calculation differences between AAA and AXB to the integral radiation dose (ID) on critical organs. Seven field intensity modulated radiotherapy (IMRT) plans were generated using with AAA and AXB algorithms for twenty patients with early stage left breast cancer after breast conserving surgery. Volumetric and dosimetric differences, as well as, the Dmean, V5, V20 doses of the left and right-sided lung, the Dmean, V10, V20, V30 doses of heart and the Dmean, V5, V10 doses of the contralateral breast were investigated. The mean dose (Dmean), V5, V20 doses of the left-sided lung, the Dmean, V5, V10 doses of right-sided lung, the Dmean, V10, V20, V30 doses of heart and the Dmean, V5, V10 doses of the contralateral breast were found to be significantly higher with AAA. In this research integral dose was also higher in the AAA recalculated plan and the AXB plan with the average dose as follows left lung 2%, heart 2%, contralateral breast 8%, contralateral lung 4% respectively. Our study revealed that the calculation differences between Acuros XB (AXB) and Anisotropic Analytical Algorithm (AAA) in breast radiotherapy caused serious differences on the stored integral doses on critical organs. In addition, AXB plans showed significantly dosimetric improvements in multiple dosimetric parameters.

High-speed performance self-powered short wave ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)

High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.

Dosimetric risk factors for radiation esophagitis in patients with breast cancer following regional nodal radiation

BACKGROUND Radiation esophagitis(RE)is one of the most common clinical symptoms of regional lymph node radiotherapy for breast cancer.However,there are fewer studies focusing on RE caused by hypofractionated radiotherapy(HFRT).AIM To analyze the clinical and dosimetric factors that contribute to the development of RE in patients with breast cancer treated with HFRT of regional lymph nodes.METHODS Between January and December 2022,we retrospectively analysed 64 patients with breast cancer who met our inclusion criteria underwent regional nodal intensity-modulated radiotherapy at a radiotherapy dose of 43.5 Gy/15F.RESULTS Of the 64 patients in this study,24(37.5%)did not develop RE,29(45.3%)developed grade 1 RE(G1RE),11(17.2%)developed grade 2 RE(G2RE),and none developed grade 3 RE or higher.Our univariable logistic regression analysis found G2RE to be significantly correlated with the maximum dose,mean dose,relative volume 20-40,and absolute volume(AV)20-40.Our stepwise linear regression analyses found AV30 and AV35 to be significantly associated with G2RE(P<0.001).The optimal threshold for AV30 was 2.39 mL[area under the curve(AUC):0.996;sensitivity:90.9%;specificity:91.1%].The optimal threshold for AV35 was 0.71 mL(AUC:0.932;sensitivity:90.9%;specificity:83.9%).CONCLUSION AV30 and AV35 were significantly associated with G2RE.The thresholds for AV30 and AV35 should be limited to 2.39 mL and 0.71 mL,respectively.

Impacts of radiation therapy on quality of life and pain relief in patients with bone metastases

Bone metastases(BM)are a common complication in advanced cancer patients,significantly contributing to morbidity and mortality due to their ability to cause pain,fractures,and spinal cord compression.Radiation therapy(RT)is vital in managing these complications by targeting metastatic lesions to ease pain,improve mobility,and reduce the risk of skeletal-related events such as fractures.Evidence supports the effectiveness of RT in pain relief,showing its ability to provide significant palliation and lessen the need for opioid painkillers,thereby enhancing the overall quality of life(QoL)for patients with BM.However,optimizing RT outcomes involves considerations such as the choice of radiation technique,dose fractionation schedules,and the integration of supportive care measures to mitigate treatment-related side effects like fatigue and skin reactions.These factors highlight the importance of personalized treatment planning tailored to individual patient needs and tumor characteristics.This mini-review aims to provide comprehensive insights into the multifaceted impacts of RT on pain management and QoL enhancement in BM patients,with implications for refining clinical practices and advancing patient care through the synthesis of findings from various studies.

New insights for pelvic radiation disease treatment:Multipotent stromal cell is a promise mainstay treatment for the restoration of abdominopelvic severe chronic damages induced by radiotherapy

Radiotherapy may induce irreversible damage on healthy tissues surrounding the tumor. It has been reported that the majority of patients receiving pelvic radiation therapy show early or late tissue reactions of graded severity as radiotherapy affects not only the targeted tumor cells but also the surrounding healthy tissues. The late adverse effects of pelvic radiotherapy concern 5% to 10% of them, which could be life threatening. However, a clear medical consensus concerning the clinical management of such healthy tissue sequelae does not exist. Although no pharmacologic interventions have yet been proven to efficiently mitigate radiotherapy severe side effects, few preclinical researches show the potential of combined and sequential pharmacological treatments to prevent the onset of tissue damage. Our group has demonstrated in preclinical animal models that systemic mesenchymal stromal cell(MSC) injection is a promising approach for the medical management of gastrointestinal disorder after irradiation. We have shown that MSCs migrate to damaged tissues and restore gut functions after irradiation.We carefully studied side effects of stem cell injection for further application in patients. We have shown that clinical status of four patients suffering from severe pelvic side effects resulting from an over-dosage was improved following MSC injection in a compationnal situation.

Radiation of a TM mode from an open end of a three-layer dielectric capillary

Modern trends in beam-driven radiation sources include the interaction of Cherenkov wakefields in open-ended circular waveguides with complicated dielectric linings, with a three-layer dielectric capillary recently proposed to reduce radiation divergence being a representative example [Opt. Lett. 45 5416(2020)]. We present a rigorous approach that allows for an analytical description of the electromagnetic processes that occur when the structure is excited by a single waveguide TM mode. In other words, the corresponding canonical waveguide diffraction problem is solved in a rigorous formulation. This is a continuation of our previous papers which considered simpler cases with a homogeneous or two-layer dielectric filling. Here we use the same analytical approach based on the Wiener–Hopf–Fock technique and deal with the more complicated case of a three-layer dielectric lining. Using the obtained rigorous solution, we discuss the possibility of manipulating the far-field radiation pattern using a third layer made of a low permittivity material.

Radiation Therapy of Head and Neck Paragangliomas: Experience from Radiotherapy Department at the National Institute of Oncology in Rabat (Morocco)

Background and Purpose: Paragangliomas are rare tumors of the head and neck. Their management remains problematic and varies considerably depending on the center. This study reported 14 years of experience in the management of head and neck paraganglioma (HNPGls). We aimed to assess the therapeutic results of these tumors in terms of local control and overall survival. Materials and Methods: We included 16 patients followed for HNPGls and treated by radiotherapy from January 2006 to June 2018 in the National Institute of Oncology in Rabat. Results: The median age was 44.5 years (15 - 67). 13 patients were female and three male with a sex ratio of 4.3. Cervical mass was the common sign (56.3%). All patients received radiation therapy. This radiation was exclusive in 43.7% of cases or adjuvant to partial surgical resection in 56.3%. The median dose of radiotherapy was 54 Gy (46 - 60) and it was delivered by a three-dimensional conformal radiotherapy technique in 15 patients and volumetric modulated arc therapy in one. There were few acute complications such as grade I and II mucositis and dermatitis. After a median follow-up of 5.6 years (2 - 13.4), local control, defined by radiological stability or regression, was obtained in 14 patients, two patients progressed and one died. Progression-free survival rates at 5 and 7 years were 93.8% and 78.1% respectively, and overall survival at 5 and 7 years was 92.3%. Conclusions: Surgery is the first-line treatment for HNPGls. When surgery is not possible or incomplete, radiotherapy has its place in the therapeutic strategy of this rare disease for long-term local control.

Flexibility potential of Cs_(2)BX_(6)(B=Hf,Sn,Pt,Zr,Ti;X=I,Br,Cl)with application in photovoltaic devices and radiation detectors

As interest in double perovskites is growing,especially in applications like photovoltaic devices,understanding their mechanical properties is vital for device durability.Despite extensive exploration of structure and optical properties,research on mechanical aspects is limited.This article builds a vacancyordered double perovskite model,employing first-principles calculations to analyze mechanical,bonding,electronic,and optical properties.Results show Cs_(2)Hfl_(6),Cs_(2)SnBr_(6),Cs_(2)SnI_(6),and Cs_(2)PtBr_(6)have Young's moduli below 13 GPa,indicating flexibility.Geometric parameters explain flexibility variations with the changes of B and X site composition.Bonding characteristic exploration reveals the influence of B and X site electronegativity on mechanical strength.Cs_(2)SnBr_(6)and Cs_(2)PtBr_(6)are suitable for solar cells,while Cs_(2)HfI_(6)and Cs_(2)TiCl_(6)show potential for semi-transparent solar cells.Optical property calculations highlight the high light absorption coefficients of up to 3.5×10^(5) cm^(-1)for Cs_(2)HfI_(6)and Cs_(2)TiCl_(6).Solar cell simulation shows Cs_(2)PtBr_(6)achieves 22.4%of conversion effciency.Cs_(2)ZrCl_(6)holds promise for ionizing radiation detection with its 3.68 eV bandgap and high absorption coefficient.Vacancy-ordered double perovskites offer superior flexibility,providing valuable insights for designing stable and flexible devices.This understanding enhances the development of functional devices based on these perovskites,especially for applications requiring high stability and flexibility.

Visualizing the Spin & Radiation of the Extended Electron in Magnetic Field

This article presents illustrations of an extended model of the electron to visualize how it spins and radiates in the external magnetic field. A time-varying magnetic field B produces a rotational induced electric field E which rotates (spins) the electron about its axis. In time-constant magnetic field: the electron radiates the cyclotron radiation. In time-varying magnetic field: synchrotron radiation is generated. The couplings between spin, acceleration and radiation will be discussed.

Heuristic Estimation of the Vacuum Energy Density of the Universe: Part II-Analysis Based on Frequency Domain Electromagnetic Radiation

In Part I of this paper, an inequality satisfied by the vacuum energy density of the universe was derived using an indirect and heuristic procedure. The derivation is based on a proposed thought experiment, according to which an electron is accelerated to a constant and relativistic speed at a distance L from a perfectly conducting plane. The charge of the electron was represented by a spherical charge distribution located within the Compton wavelength of the electron. Subsequently, the electron is incident on the perfect conductor giving rise to transition radiation. The energy associated with the transition radiation depends on the parameter L. It was shown that an inequality satisfied by the vacuum energy density will emerge when the length L is pushed to cosmological dimensions and the product of the radiated energy, and the time duration of emission is constrained by Heisenberg’s uncertainty principle. In this paper, a similar analysis is conducted with a chain of electrons oscillating sinusoidally and located above a conducting plane. In the thought experiment presented in this paper, the behavior of the energy radiated by the chain of oscillating electrons is studied in the frequency domain as a function of the length L of the chain. It is shown that when the length L is pushed to cosmological dimensions and the energy radiated within a single burst of duration of half a period of oscillation is constrained by the fact that electromagnetic energy consists of photons, an inequality satisfied by the vacuum energy density emerges as a result. The derived inequality is given by where is the vacuum energy density. This result is consistent with the measured value of the vacuum energy density, which is 5.38 × 10-10 J/m. The result obtained here is in better agreement with experimental data than the one obtained in Part I of this paper with time domain radiation.