Consequences of gamma-ray irradiation on structural and electronic properties of PEDOT:PSS polymer in air and vacuum environments

In this work, the effects of gamma-ray irradiation (up to 3 kGy) on the structural and electronic properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), irradiated in air and vacuum environments are systematically investigated. Raman spectroscopy indicates that there is no significant change in structural conformation of PEDOT:PSS film after gamma-ray irradiation. However, the conductivity of the film decreases as a function of dose in both air and vacuum environments, which can be deduced as a result of defects created in the structure. Hall effect measurements showed higher carrier concentration when the samples are irradiated under vacuum in comparison to the air environment, whereas mobility decreases as a function of dose irrespective of the environment. Furthermore, the electron spin resonance spectra provided evidence of the evolution of polaron population after gamma-ray exposure of 3 kGy, due to the decrease in charge delocalization and molecular ordering of the molecules. This decrease in conductivity and mobility of the PEDOT:PSS films irradiated in air and vacuum environments can be mainly ascribed to the defects and radical formation after gamma-ray exposure, favoring chain scission or cross-linking of the polymers.

Effects of gamma-ray irradiation (up to 3 kGy) on the structural and electronic properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), irradiated in air and vacuum environments are systematically investigated.     

Impact of the Early Phase of the COVID-19 Pandemic on Medical Student Well-Being: a Multisite Survey

BackgroundThe COVID-19 pandemic drastically impacted medical student experiences. Little is known about the impact of the pandemic on student well-being and protective factors for burnout.ObjectiveAssess US medical student burnout, stress, and loneliness during the initial phase of the pandemic, compare results to pre-pandemic data, and identify risk factors for distress and protective factors to inform support interventions.DesignCross-sectional survey of medical students conducted between May and July 2020.Participants3826 students from 22 medical schools.Main MeasuresBurnout (MBI-HSS), stress (PSS-10), loneliness (UCLA scale), and student experiences. Compared burnout and stress to pre-pandemic studies (2010–2020).Key ResultsOf 12,389 students, 3826 responded (31%). Compared to pre-pandemic studies, burnout was lower (50% vs. 52%, P = 0.03) while mean stress was higher (18.9 vs. 16.0, P < 0.001). Half (1609/3247) reported high (≥ 6/9) loneliness scores. Significant differences were found in burnout and stress by class year (P = 0.002 and P < 0.001) and race (P = 0.004 and P < 0.001), with the highest levels in second- and third-year students and Black, Asian, or other racial minority students. Students experiencing financial strain or racism had higher burnout and stress (P < 0.001 for all). Respondents with COVID-19 diagnoses in themselves or family members had higher stress (P < 0.001). Nearly half (1756/3569) volunteered during the pandemic, with volunteers reporting lower burnout [48% (782/1639) vs. 52% (853/1656), P = 0.03].ConclusionsWhile stress was higher compared to pre-pandemic data, burnout was significantly lower. Higher burnout and stress among Black, Asian, and other racial minority students and those who experienced financial strain, racism, or COVID-19 diagnoses likely reflect underlying racial and socioeconomic inequalities exacerbated by the pandemic and concurrent national racial injustice events. Volunteer engagement may be protective against burnout. Schools should proactively support vulnerable students during periods of stress.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11606-022-07497-2.KEY WORDS: medical student well-being, mental health, burnout, stress, COVID-19 pandemic, stress     

Outcome of radial head preserving operations in missed Monteggia fracture in children

Background:

The dislocated radial head in missed Monteggia fracture loses its concave articular surface and displays hypertrophic changes and flattened humeral capitellum configuration, thereby limiting the range of motion. We evaluated the results of open reduction in missed Monteggia fractures by various techniques.

Materials and Methods:

Sixty-three missed Monteggia fractures were included in the analysis. We performed four combinations of operation: Group I: 22 patients treated with modified Hirayama ulnar osteotomy plus annular ligament reconstruction with free Palmaris longus grafting; Group II:18 patients treated with modified Hirayama ulnar osteotomy plus annular ligament reconstruction by the Bell Tawse''s procedure; Group III-9: patients treated with only modified Hirayama''s osteotomy; and Group IV: 14 patients treated with transverse osteotomy of ulna and annular ligament reconstruction by the Bell Tawse''s procedure. During followup these cases were assessed for the following parameters: 1) range of motion and 2) mayo elbow performance index (MEPI). Results were noted on follow ups at 3, 6, 12 months and then on yearly basis. Sixty-three patients were followed up for an average duration of 5.6 years (range 3-8 years).

Results:

The mean range of motion was increased by 45°, 30°, 45°, 20° for Group I, II, III and IV respectively. The average increase in MEPI scores was also almost on the same lines. There was one case of frank dislocation in group III and six cases of subluxation, two each in Groups II, III, and IV. For Annular ligament reconstruction, amongst two procedures, Groups II and IV (Bell Tawse group), had a significant extension lag contributing to the lower increase in the range of motion as compared to the Palmaris longus reconstruction group (group I).

Conclusion:

Hirayama''s osteotomy is inherently more stable than the simple transverse osteotomy and it should be combined with annular ligament reconstruction. Palmaris longus graft for ligament reconstruction provides more stability as compare to Bell Towse''s procedure.     

OnabotulinumtoxinA for Treatment of Focal Cancer Pain After Surgery and/or Radiation

Objective. To report the relief from refractory focal post-radiation and/or postsurgical cancer pain after local treatment with onabotulinumtoxinA. Setting and Design. We studied the effect of onabotulinumtoxinA in seven cancer patients who suffered from severe focal pain (visual analog scale?>5) at the site of local surgery or radiotherapy or both. OnabotulinumtoxinA (20-100 units) was injected into the focal pain areas (skin or muscle or both). Five of seven patients were followed beyond 1 year (1.5-5 years) with repeat treatment. Results. All seven patients reported a significant improvement in pain (mean drop in visual analog scale score of 5.1). They described their response on the patient global assessment as satisfactory (two patients) or very satisfactory (five patients). Six of seven patients found the pain relief associated with significant improvement in quality of life. One patient developed weakness of jaw muscles after bilateral masseter injection that was not observed during second injection (reduced dose). Improvements with treatment persisted with repeat injections during long-term follow-up (five patients). Conclusion. Local treatment with onabotulinumtoxinA can significantly reduce pain and improve quality of life in cancer patients suffering from pain in the area of surgery and radiation and was well tolerated in cancer patients.     

Subretinal hyperreflective material morphology in neovascular age-related macular degeneration: A case control study

Purpose:The aim of this study was to evaluate the association of morphological features of subretinal hyperreflective material (SHRM) with visual acuity (VA), geographic atrophy (GA) and scar formation in eyes with neovascular age-related macular degeneration (neovascular AMD) and to compare with controls of neovascular AMD without SHRM.Methods:Retrospective analysis of 157 wet AMD eyes with SHRM and 50 eyes without SHRM treated with Anti-VEGF. Baseline spectral domain-OCT characteristics (SHRM location, height, width, area, reflectivity, border definition) were collected and were correlated with VA at baseline, 3, 6, 12 months and looked for development of scar and geographical atrophy (GA) and were compared to the control group.Results:When compared to the control, baseline parameters with a significant predictive value of 12-VA were presence of SHRM, foveal involvement of SHRM, high reflective SHRM, well-defined SHRM borders and thick SHRM. VA was decreased with greater SHRM height, width and area (P < 0.001). Decreasing reflectivity of SHRM lesions and disappearance of SHRM correlated with better VA at 12 months (P < 0.05). At 12 months, scar and GA was present more often in eyes with persistent SHRM than in eyes with SHRM that resolved and those without SHRM in the control group.Conclusion:SHRM can be considered as a surrogate OCT biomarker in predicting final visual outcome in neovascular age-related macular degeneration. Baseline parameters predicting poorer vision at 12-follow-up were presence of SHRM involving the fovea, well-defined SHRM borders, greater SHRM height, width and area and persistence of SHRM with Anti-VEGF therapy.     

2D BeP2 monolayer: investigation of electronic and optical properties by driven modulated strain

Recently, the two-dimensional (2D) material beryllium diphosphide (BeP₂) has attracted significant attention for potential device applications due to its Dirac semimetal state, dynamic and thermal stability, and high carrier mobility. In this work, we investigated its electronic and optical properties under biaxial Lagrangian strain using density functional theory (DFT). Electronic band gaps and effective charge carrier mass were highly sensitive to the Lagrangian strain of BeP₂ monolayer. The bandgaps of BeP₂ varied from 0 eV to 0.30 eV for 2% to 8% strain, where the strain range is based on the final stable condition of the system. The absorption spectra for the dielectric properties show the highest absorption peaks in the infrared (IR) region. These abundant strain-dependent studies of the BeP₂ monolayer provide guidelines for its application in infrared sensors and devices.

BeP₂ monolayer is a promising material for the novel IR optical device.