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Electrical characterization of sputter-induced deep levels in GaN thin films synthesized by electrodeposition
Ali, Abdulraoof Idriss Ahmed; Taghizadeh, Fatemeh; Janse van Rensburg, Pieter Johan; Meyer, Walter Ernst; Nel, Jacqueline Margot; Venter, Andre (Elsevier, 2026-01)
This paper reports on the presence of deep-level defects in polycrystalline GaN thin films induced during the sputter deposition of Au Schottky barrier diodes (SBDs). The n-GaN films, with a thickness of approximately 300 nm were electrodeposited on (111) Si substrates using a low-cost method and a current density of 3 mA.cm-2 for 3 hours. Structural analysis by X-ray diffraction, scanning electron microscopy, and atomic force microscopy confirmed the polycrystalline nature and good quality of the films. Deep-level transient spectroscopy (DLTS) revealed a broad, asymmetric peak around 265 K in the as-deposited SBDs, indicating the presence of multiple defects. Laplace DLTS resolved four distinct defects with energies ranging between 0.40 eV and 0.60 eV. Thermal annealing between 450 - 500 K increased the reverse leakage current with only minor changes in the forward-bias characteristics. However, annealing at 550 K significantly reduced the leakage current by two orders of magnitude and improved the rectification ratio by one order of magnitude. All samples exhibited significant series resistance. Capacitance-voltage measurements revealed a reduction in the free carrier density near the surface, suggesting the sputter process introduced additional deep level defects. Furthermore, the deep-level energy (and therefore the likely defect composition) was found to be sensitive to the annealing temperature. HIGHLIGHTS • Sputtering-induced deep levels identified by Laplace DLTS. • Evolution of these defects during annealing at 450-550 K. • Correlation of the deep-level spectra with important diode parameters (Rs, Φb, n). • Enhanced diode performance after 550 K annealing.
The role of welfare regimes on socioeconomic inequalities in edentulism : a cross-national analysis of 40 countries
Celeste, Roger Keller; Guarnizo-Herreño, Carol C.; Fritzell, Johan; Costa, Francine S.; Ayo-Yusuf, Olalekan Abdulwahab; Barros, Aluisio J.D.; Li, Huihua; Hariyani, Ninuk; Hackley, Donna M.; Blanco, Silvana; Gamonal, Jorge A.; Maupomé, Gerardo; Watt, Richard Geddie; Peres, Marco Aurélio De A. (Elsevier, 2026-04)
BACKGROUND : We aim to evaluate the association between welfare regimes and edentulism (total tooth loss) and to investigate whether welfare regimes modify the magnitude of socioeconomic inequalities in edentulism. METHODS : The Lancet Commission on Oral Health gathered and analysed nationally representative available data from 40 high, middle- and low-income countries, collected between 2007 and 2018. The study included 117,397 individuals 20 years or older. The outcome was edentulism, defined as the absence of all natural teeth. We categorised countries into seven welfare regimes, which served as both the primary exposure and an effect modifier. Individual-level variables included sex, age and a composite measure of socioeconomic position: “wealth” measured in quintiles. Inverse probability of treatment weight and multilevel logistic regression were employed to estimate the odds of being edentulous, and cross–level interaction terms between wealth and country factors. FINDINGS : Individuals at the lowest wealth quintile had the highest prevalence of edentulism in all regimes. The highest age-sex standardised prevalence was found in Eastern European countries (8.4%, 95% Confidence Interval: 7.6–9.3), followed by Corporative (8.1%, 95% CI: 7.0–9.3), while the lowest was among the Insecurity regime (0.8%, 95% CI: 0.4–1.5), followed by the Scandinavian regime (4.7%, 95% CI: 3.5–6.1). Liberal countries presented the highest magnitude of absolute and relative inequalities, where the lowest quintile had OR = 20.6 (95% CI: 15.3–27.8) times higher likelihood of being edentulous and 17.3 percentage points (pp) higher prevalence. Low-income countries in the Insecurity regime presented the lowest level of inequality. Among high- and upper-middle income countries, the Scandinavian regime had the lowest absolute inequalities (5.5 pp difference between highest and lowest quintiles). The Informal Security regime had the lowest relative differences between the highest and lowest quintiles (OR = 2.20, 95% CI: 1.06–4.59). INTERPRETATION : Our findings indicate that some welfare regime policies may enhance oral health while decreasing socioeconomic inequalities. Higher prevalence and inequalities among industrialised countries may reflect higher levels of oral health hazards.
Natural acids as catalysts for the continuous flow production of the green solvent 2,2,5,5-tetramethyltetrahydrofuran
Currie, Bernice Mercia; Van Vuuren, Estefan; Jugmohan, Jaimee; Panayides, Jenny Lee; Riley, Darren Lyall (Elsevier, 2026-06)
As the demand for chemists to adhere to green chemistry principles increases, so does the demand for green solvents. Unfortunately, many green solvents, such as 2,2,5,5-tetramethyltetrahydrofuran (TMTHF), are costly and difficult to source. Traditional synthesis of TMTHF from 2,5-dimethyl-2,5-hexanediol has been reported to be catalysed by acids such as phosphoric and sulfuric acid, or, more recently, by H-beta zeolite. Although H-beta zeolite catalysts are high-yielding and selective, the energy required for their regeneration is high, and their production has questionable environmental impacts. A new approach was developed using flow technologies and naturally occurring acids as catalysts for TMTHF synthesis. Flow technologies are scalable, safe, efficient, and reproducible for daily chemical reactions, aligning with principles of green chemistry. This study observed several key improvements, including i) the use of a natural acid as a catalyst, ii) the use of water as a solvent, and iii) a continuous process for multigram-scale synthesis of TMTHF using citric acid monohydrate, with a yield of 72 %, resulting in a throughput of 8.24 g h−1 (9.43 kg L −1 h−1 space-time yield).
Managing variations in meaning : guidance for using complexity and related terms
Sutherland, Joshua; Beale, Dean; Dazzi, Francesco; Singer, Janet; Smith, Gary; Oosthuizen, Rudolph; Lanza, Alfonso; Cureton, Ken; McKinney, Dorothy (Wiley, 2026-01)
The term “Complexity” is widely used across disciplines, where it often represents distinct but related concepts such as complicatedness, emergence, difficulty, uncertainty, and chaos. This variability in usage can create miscommunication and misunderstanding, even within structured organizations like the International Council on Systems Engineering (INCOSE). This paper addresses this challenge by offering guidance tailored to three primary audiences—General/Casual, Practitioner, and Research—on using and interpreting “Complexity” effectively across trans-disciplinary contexts. Unlike efforts that prescribe a single definition, the approach here respects the variety of interpretations while providing techniques and ontologies to clarify usage. To illustrate, the paper compares different “Complexity” definitions, fostering awareness of both the similarities and distinctions. By promoting a common understanding, rather than a definition, this paper lays essential groundwork for future initiatives aimed at developing a unified scientific basis for “Complexity”, enabling clearer, more consistent communication, and application.
Perception of ecosystem services use across vegetation types and land use zones in Vhembe Biosphere Reserve, South Africa
Chirwa, Paxie W.; Tshidzumba, Ratsodo Phillip; Makhubele, Lucky; Araia, Mulugheta Ghebreslassie; Honold, Martin A.; Hilmers, Torben; Pretzsch, Hans (MDPI, 2026-01)
Sustainable management of ecosystem services (ESs) is critical for balancing human well-being with conservation goals in biosphere reserves. This study examined the spatial and socio-demographic variation in the use and perceived importance of provisioning, regulating, supporting, and cultural ESs across different vegetation types and land use zones in the Vhembe Biosphere Reserve (VBR), South Africa. Household surveys were administered to 447 randomly selected households in six rural communities. Descriptive statistics, Chi-square tests, Kruskal–Wallis tests, and Friedman mean ranking analysis were employed. Results revealed significant differences (p < 0.05) in ES distribution and value across vegetation types, land use categories, and household characteristics, including income, education, age, and gender. Provisioning services, particularly fuelwood, wild fruits, and wild vegetables, were most intensively utilized in Mountain Woodland Moist and Ironwood Forest areas due to accessibility and limited livelihood alternatives. Regulating and supporting services, including water purification, erosion control, and habitat provision, were associated with forested and traditionally protected areas. Cultural services reflected strong socio-cultural ties, especially in sacred and tourism-associated landscapes. Overall, the study highlights the multifunctional importance of forested and agroforestry systems in rural livelihoods, emphasizing the need for integrated, culturally informed, and ecologically sound land use planning to support sustainable development in the VBR.