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Stabilizing metal halide perovskite films via chemical vapor deposition and cryogenic electron beam patterning
(John Wiley and Sons Inc, 2025) Arendse, Christopher Joseph; Burns, Randy; Chiaro, Dylan
Halide perovskites are hailed as semiconductors of the 21st century. Chemical vapor deposition (CVD), a solvent-free method, allows versatility in the growth of thin films of 3- and 2D organic–inorganic halide perovskites. Using CVD grown methylammonium lead iodide (MAPbI3) films as a prototype, the impact of electron beam dosage under cryogenic conditions is evaluated. With 5 kV accelerating voltage, the dosage is varied between 50 and 50000 µC cm−2. An optimum dosage of 35 000 µC cm−2 results in a significant blue shift and enhancement of the photoluminescence peak. Concomitantly, a strong increase in the photocurrent is observed. A similar electron beam treatment on chlorine incorporated MAPbI3, where chlorine is known to passivate defects, shows a blue shift in the photoluminescence without improving the photocurrent properties. Low electron beam dosage under cryogenic conditions is found to damage CVD grown 2D phenylethlyammoinum lead iodide films. Monte Carlo simulations reveal differences in electron beam interaction with 3- and 2D halide perovskite films. © 2024 Wiley-VCH GmbH.
Fraud as legitimate retribution for colonial injustice: neutralization techniques in interviews with police and online romance fraud offenders
(Routledge, 2025) Lazarus, Suleman Ibrahim; Hughes, Mariata; Button, Mark
This qualitative research examines the phenomenon of online romance fraud, exploring it from contrasting perspectives. The study engaged two distinct groups of participants: (1) fraudsters actively involved in online romance scams (commonly referred to as “Sakawa Boys”) and (2) police officers with experience in investigating and policing internet crimes. We explore the usefulness of neutralization techniques in interpreting data within the cultural context of individuals’ subjective experiences. Thematic analysis of data reveals that both offenders and police officers employ certain neutralization techniques, such as denial of responsibility, condemnation of the condemners, and appeals to higher loyalties, to justify their conduct. In particular, online romance offenders invoke higher loyalties, rationalizing their actions as reparative justice for colonial exploitation and framing their fraud as a means of reclaiming wealth unjustly taken during colonial rule. The findings suggest that participants perceive the enduring legacy of colonialism as a key factor driving the production of cybercrime. This research contributes to the scant body of direct testimonies from romance fraud offenders, which are significantly rarer than those from police officers, providing valuable insights into this global phenomenon. Methodologically and theoretically, this research contributes to understanding the global phenomenon of scammers targeting individuals worldwide. © 2025 The Author(s). Published with license by Taylor & Francis Group, LLC.
Giant dielectric constant in calcium manganese oxide ceramics
(Elsevier Ltd, 2025) Mahapatro,, Ajit; Pant, Megha
Giant dielectric constant (GDC) materials have been promising for their potential utilization in multifunctional devices, including high-performance energy storage and development of efficient electronic elements. The preliminary charge transport study of ceramics possessing GDC would provide insight for utilization in world-wide applications. GDC of ~106 is realized in the temperature range of 133–593 K through perfectly dense calcium manganese oxide (CaMnO3) ceramics prepared using hot-press technique. The dc-conductivity and dielectric relaxation spectra exhibit Mott-variable range hopping in the temperature range of 133–393 K and small polaron hopping above 493 K. The Nyquist plot provides an equivalent model with series combination of two sets of parallelly connected circuits comprising of resistance and constant phase element, attributed to the contributions from grains and grain boundaries. The ac-conductivity suggests the presence of non-overlapping small polaron tunneling in temperature range of 133–333 K and overlapping large polaron tunneling above 333 K. An electronpolaron band located at 0.27 eV below the conduction band edge is demonstrated with consideration of polaron hopping and band gap energy. Scaling procedure employed to the ac-conductivity universality evidences the corrected Summerfield model and presence of Coulomb interaction between the charge carriers. The in-depth study of the frequency and temperature dependent electric and dielectric properties demonstrates GDC over a wide frequency range of 1 Hz ̶10 MHz, and low loss tangent above 10 kHz in the currently prepared perfectly dense CaMnO3 ceramics and suggests its suitability for engineering charge storage devices in the radio frequency region.
Smoked or bewitched? the relationship between cannabis use and mental illness among the shona persons in Zimbabwe
(Springer, 2025) Maja, Jakarasi
The metanarrative of biomedicine and “psy” discipline (psychology, psychoanalysis, psychiatry etc.) asserts that cannabis use is one of the fundamental causes of mental illness among different men in the Rushinga district of Zimbabwe. These metanarratives, however, appear to have universalised, medicalised and marginalised the conception and representation of mental illness as enmeshed in local epistemologies and ontologies of mental illness. Based on local epistemologies, elders in Diwa largely trace mental illness to discursive sociocultural explanations rarely linked to cannabis use. This paper answers the central question: How is the use of cannabis by different persons related to mental illness in the Rushinga district? I argue that community members, health providers and police officers want to think of persons, especially men, with mental illness as “mad” and immoral cannabis users who brought illnesses upon themselves and lack personal responsibility based on Western neoliberal and biomedical metanarratives. However, this framing is not helpful, it is detrimental to treatment and social reputation, as it bypasses local cultural explanations that may be protective and that offer clearer guidelines for treatment. © The Author(s) 2025.
Examining the psychometric properties of the patient health questionnaire-9 and generalized anxiety disorder-7 among young urban South African women
(Elsevier B.V., 2025) Nyati, Lukhanyo H; Hart, Claire; Elizabeth Draper, Catherine Elizabeth
Background: Valid, reliable, and easy-to-administer scales are crucial for identifying mental health conditions, especially in LMICs where such scales tend not to be validated. This study aims to address this gap by investigating the psychometric properties and factorial structure of the PHQ-9 and GAD-7 in a sample of young women in Soweto, South Africa. Methods: The PHQ-9 and GAD-7 were administered to 6028 women aged 18–28 years old. Cronbach's alpha, Mokken scale analysis, and Confirmatory Factor Analysis were used to provide support for the internal consistency and construct validity of these scales. Results: Both scales demonstrated good internal consistency (α = 0.81 for PHQ-9 and α = 0.84 for GAD-7). Internal consistency reliability was further supported by positive inter-item correlations and item-by-scale correlations for all items on both measures. CFA of the PHQ-9 and GAD-7 showed a reasonable fit for the 1-factor model and 2-factor models (depression and anxiety with somatic and cognitive subtypes). Limitations: This study was limited to young African women in urban Soweto who were proficient in English, which may affect generalizability. Differences in language or cultural context may impact the accuracy and applicability of these scales to other African populations. Conclusion: The PHQ-9 and GAD-7 are valid and reliable for identifying psychological distress in the studied population. Despite showing good psychometric properties, further diagnostic assessment is needed to confirm clinical diagnoses. The scales are useful for identifying those at risk but not a substitute for comprehensive diagnostic evaluations. © 2024 The Authors