Research Articles (Physics)
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Item The VLA-COSMOS 3 GHz large project : polarised source counts and catalogueRanchod, S.; Mao, S.A.; Deane, Roger; Smolcic, V.; Wagenveld, J.D.; Bondi, M.; Mooley, K.; Schinnerer, E. (EDP Sciences, 2026-08)Please read abstract in the article.Item The LOFAR Two-metre Sky Survey : VII. Third data releaseShimwell, T.W; Hardcastle, M.J.; Tasse, C.; Drabent, A.; Botteon, A.; Williams, W.L.; Best, P.N.; Röttgering, H.J.A.; Brüggen, M.; Brunetti , G.; Callingham, J.R.; Chyzy , K.T.; Conway, J.E.; De Gasperin, F.; Haverkorn, M.; Horellou, C.; Jackson, N.; Miley, G.K.; Morabito, L.K.; Morganti, R.; O’Sullivan, S.P.; Schwarz, D.J.; Smith, D.J.B.; Van Weeren, R.J.; Vedantham, H.K.; White, G.J.; Ahmadi, A.; Alegre, L.; Arias, M.; Asabere, B.; Bahr-Kalus, B.; Barkus, B.; Bilicki, M.; Böhme, L.; Brentjens, M.; Brienza, M.; Bomans, D.J.; Bonafede, A.; Bonato, M.; Bonnassieux, E.; Boxelaar, J.M.; Camera, S.; Cassano, R.; Chilufya, J.; Cianfaglione, M.; Croston, J.H.; Cuciti, V.; Dabhade, P.; De Rubeis, E.; De Jong, J.M.G.H.J.; Dallacasa, D.; Dettmar, R.J.; Duncan, K.J.; Di Gennaro, G.; Edler, H.W.; Groeneveld, C.; Gürkan, G.; Hajduk, M.; Hale, C.L.; Heesen, V.; Hoang, D.N.; Hoeft, M.; Holties, H.; Horton, M.A.; Iacobelli , M.; Jamrozy , M.; Horton, M.A.; Iacobelli, M.; Jamrozy, M.; Jarvis, M.J.; Jelic, V.; Kadler, M.; Kondapally, R.; Kunert-Bajraszewska, M.; Loose, M.; Magliocchetti, M.; Małek, K.; Manzano, C.; McKean, John P.; Mevius, M.; Mingo, B.; Miskolczi, A.; Misra, A.; Moldón, J.; Nair, D.G.; Nakoneczny, S.J.; Orru, E.; Pashapour-Ahmadabadi, M.; Pasini, T.; Petley, J.; Pierce, J.C.S.; Prandoni, I.; Rafferty, D.; Rajpurohit, K.; Riseley, C.J.; Roberts, I.D.; Sethi, S.; Shulevski, A.; Stein, M.; Stuardi, C.; Sweijen, F.; Ter Veen, S.; Timmerman, R.; Vaccari, M.; Wijnholds, S. (EDP Sciences, 2026-03)We present the third data release of the LOFAR Two-metre Sky Survey (LoTSS-DR3). The survey images cover 88% of the northern sky and were created from 12 950 h of data (18.6 PB) accumulated over 10.5 years. Producing the images took 20 million core hours of processing through direction-independent and direction-dependent calibration pipelines that correct for instrumental effects as well as spatially and temporally varying ionospheric distortions. In our 120–168 MHz continuum mosaic images with an angular resolution of 6″ (9″ below declination 10°) we catalogue 13 667 877 sources, formed from 16 943 656 Gaussian components. The scatter in the astrometric precision approximately follows the expected noise-like behaviour but with an additional systematic component of at least 0.24″ that is likely due to calibration imperfections. The random flux density scale error is 6%, while the systematic offset was previously shown to be within 2%. The median sensitivity of our mosaics is 92 μJy beam−1, improving to 68 μJy beam−1 at high observing elevations, but degrading to 183 μJy beam−1 at the celestial equator due to station area projection effects. Completeness simulations, accounting for realistic source models, time- and bandwidth-smearing effects, and astrometric errors, indicate that we detect more than 95% of compact sources with integrated flux densities exceeding 9 times the local root mean square (RMS) noise. However, the recovered source counts in a particular integrated flux density bin do not match the injected counts until flux densities exceed 45 times the local RMS noise. The Euclidean-normalised differential source counts derived from the survey constrain the radio source population over five orders of magnitude and are in good agreement with previous deep and wide-area surveys. All data products are publicly available, including catalogues, individual-field Stokes I, Q, U, and V images, mosaicked Stokes I images, and uv data with associated direction-dependent calibration solutions.Item Full-polarization millimeter wavelength variability of Sagittarius A* during the 2018 EHT campaignAlbentosa-Ruíz, Ezequiel ; Washington, Jasmin E.; Marchili, Nicola; Martí-Vidal, Ivan; Goddi, Ciriaco; Wielgus, Maciek; Mus, Alejandro; Ricarte, Angelo; Marrone, Daniel P.; Salas, Leon D.S.; Iwata, Yuhei; Carlos, Douglas F.; Tetarenko, Alexandra J.; Moriyama, Kotaro; Dhruv, Vedant; Akiyama , Kazunori; Alberdi , Antxon; Alef , Walter; Algaba , Juan Carlos; Anantua , Richard; Asada , Keiichi; Azulay , Rebecca; Bach , Uwe; Baczko , Anne-Kathrin; Ball , David; Baloković , Mislav; Bandyopadhyay , Bidisha; Barrett , John; Bauböck , Michi; Benson , Bradford A.; Bintley , Dan; Blackburn , Lindy; Blundell , Raymond; Bouman , Katherine L.; Bower , Geoffrey C.; Bremer , Michael; Brissenden , Roger; Britzen , Silke; Broderick , Avery E.; Broguiere , Dominique; Bronzwaer , Thomas; Bustamante , Sandra; Carlstrom , John E.; Chael , Andrew; Chan , Chi-kwan; Chang , Dominic O.; Chatterjee , Koushik; Chatterjee , Shami; Chen , Ming-Tang; Chen , Yongjun; Cheng , Xiaopeng; Christian , Pierre; Cho , Ilje; Conroy , Nicholas S.; Conway , John E.; Crawford , Thomas M.; Crew , Geoffrey B.; Cruz-Osorio , Alejandro; Cui , Yuzhu; Curd , Brandon; Dahale , Rohan; Davelaar , Jordy; De Laurentis , Mariafelicia; Deane, Roger; Dempsey , Jessica; Desvignes , Gregory; Dexter , Jason; Dihingia , Indu K.; Doeleman, Sheperd S.; Dzib, Sergio A.; Eatough, Ralph P.; Emami, Razieh; Falcke, Heino; Farah, Joseph; Fish, Vincent L.; Fomalont, Edward; Ford, H. Alyson; Foschi, Marianna; Fuentes, Antonio; Fraga-Encinas, Raquel; Freeman, William T.; Friberg, Per; Fromm, Christian M.; Galison, Peter; Gammie, Charles F.; Garcia, Roberto; Gentaz, Olivier; Geertsema, Gertie; Georgiev, Boris; Gold, Roman; Gomez, Jose L.; Gomez-Ruiz, Arturo I.; Gu, Minfeng; Gurwell, Mark; Hada, Kazuhiro; Haggard, Daryl; Hesper, Ronald; Heumann, Dirk; Ho, Luis C.; Ho, Paul; Honma, Mareki; Huang, Chih-Wei L.; Huang, Lei; Hughes, David H.; Ikeda, Shiro; Impellizzeri, C.M. Violette; Inoue, Makoto; Issaoun, Sara; James, David J.; Jannuzi, Buell T.; Janssen, Michael; Jeter, Britton; Jiang, Wu; Jimenez-Rosales, Alejandra; Johnson, Michael D.; Jones, Adam C.; Jorstad, Svetlana; Joshi, Abhishek V.; Jung, Taehyun; Karuppusamy, Ramesh; Kawashima, Tomohisa; Keating, Garrett K.; Kettenis, Mark; Kim, Dong-Jin; Kim, Jae-Young; Kim, Jongsoo; Kim, Junhan; Kino, Motoki; Koay, Jun Yi; Kocherlakota, Prashant; Kofuji, Yutaro; Koch, Patrick M.; Koyama, Shoko; Kramer, Carsten; Kramer, Joana A.; Kramer, Michael; Krichbaum, Thomas P.; Kuo, Cheng-Yu; La Bella, Noemi; Lee, Sang-Sung; Levis, Aviad; Li, Zhiyuan; Lico, Rocco; Lindahl, Greg; Lindqvist, Michael; Lisakov, Mikhail; Liu, Jun; Liu, Kuo; Liuzzo, Elisabetta; Lo, Wen-Ping; Lobanov, Andrei P.; Loinard, Laurent; Lonsdale, Colin J.; Lowitz, Amy E.; Lu, Ru-Sen; MacDonald, Nicholas R.; Mao, Jirong; Marko, Sera; Marscher, Alan P.; Matsushita, Satoki; Matthews, Lynn D.; Medeiros, Lia; Menten, Karl M.; Mizuno, Izumi; Mizuno, Yosuke; Montgomery, Joshua; Moran, James M.; Moscibrodzka, Monika; Mulaudzi, Wanga; Mueller, Hendrik; Mueller, Cornelia; Musoke, Gibwa; Myserlis, Ioannis; Nagai, Hiroshi; Nagar, Neil M.; Nair, Dhanya G.; Nakamura, Masanori; Narayanan, Gopal; Natarajan, Iniyan; Nathanail, Antonios; Fuentes, Santiago Navarro; Neilsen, Joey; Ni, Chunchong; Nowak, Michael A.; Oh, Junghwan; Okino, Hiroki; Sanchez, Hector Raul Olivares; Oyama, Tomoaki; Ozel, Feryal; Palumbo, Daniel C.M.; Paraschos, Georgios Filippos; Park, Jongho; Parsons, Harriet; Patel, Nimesh; Pen, Ue-Li; Pesce, Dominic W.; Pietu, Vincent; PopStefanija, Aleksandar; Porth, Oliver; Prather, Ben; Principe, Giacomo; Psaltis, Dimitrios; Pu, Hung-Yi; Ramakrishnan, Venkatessh; Rao, Ramprasad; Rawlings, Mark G.; Rezzolla, Luciano; Ripperda, Bart; Roder, Jan; Roelofs, Freek; Romero-Canizales, Cristina; Ros, Eduardo; Roshanineshat, Arash; Rottmann, Helge; Roy, Alan L.; Ruiz, Ignacio; Ruszczyk, Chet; Rygl, Kazi L.J.; Sanchez, Salvador; Sanchez-Arguelles,, David; Sanchez-Portal, Miguel; Sasada, Mahito; Satapathy, Kaushik; Saurabh; Savolainen, Tuomas; Schloerb, F. Peter; Schonfeld, Jonathan; Schuster, Karl-Friedrich; Shao, Lijing; Shen, Zhiqiang; Silpa, Sasikumar; Small, Des; Sohn, Bong Won; SooHoo, Jason; Souccar, Kamal; Stanway, Joshua S.; Sun, He; Tazaki, Fumie; Tiede, Paul; Tilanus, Remo P. J.; Titus, Michael; Toma, Kenji; Torne, Pablo; Toscano, Teresa; Traianou, Efthalia; Trent, Tyler; Trippe, Sascha; Turk, Matthew; van Bemmel, Ilse; van Langevelde, Huib Jan; van Rossum, Daniel R.; Vos, Jesse; Wagner, Jan; Ward-Thompson, Derek; Wardle, John; Weintroub, Jonathan; Wharton, Robert; Wiik, Kaj; Witzel, Gunther; Wondrak, Michael F.; Wong, George N.; Wu, Qingwen; Yadlapalli, Nitika; Yamaguchi, Paul; Yfantis, Aristomenis; Yoon, Doosoo; Young, Andre; Younsi, Ziri; Yu, Wei; Yuan, Feng; Yuan, Ye-Fei; Zeng, Ai-Ling; Zensus, J. Anton; Zhang, Shuo; Zhao, Guang-Yao; Zhao, Shan-Shan (EDP Sciences, 2026-04)CONTECT : Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, provides a unique laboratory to study accretion dynamics and plasma processes near the event horizon. AIMS: We investigated the variability and polarization properties of Sgr A* using ALMA observations during the 2018 Event Horizon Telescope campaign. METHODS.: We analyzed high-cadence full-polarization light curves from ALMA at millimeter wavelengths, performed time-series analysis, and investigated the temporal behavior during an X-ray flare observed by Chandra on 2018 April 24. The variability characteristics are compared with expectations from standard accretion flow models. RESULTS.: We find low variability in total intensity (σ/μ < 10%), but significantly higher variability in linear and circular polarization (∼30% and ∼50%, respectively). A time-series analysis reveals red-noise variability, with power spectral densities between −2 and −3 across all Stokes parameters. Polarized intensity shows stable intra-day timescales, while total intensity exhibits more variable timescales, suggesting distinct emission regions, with polarization likely arising from a coherent structure. On April 24, a statistically significant inter-band delay in polarized intensity coincides with a near-simultaneous X-ray and millimeter peak that deviates from the typical delayed flare scenario. This event also features enhanced millimeter variability and coherent polarization loop evolution. The observed simultaneity challenges standard models of transient synchrotron emission with cooling delays, favoring instead a scenario of continuous energy injection in an optically thin region. CONCLUSIONS.: Our results offer new constraints on the physical mechanisms driving variability in Sgr A*, and provide key observational input for refining theoretical models of accretion and plasma behavior in the vicinity of supermassive black holes.Item Comprehensive investigation of the K2P2Pd ternary Zintl-phase semiconductor compound for energy harvesting applications by first-principles methodsMusembi, Robinson; Mbilo, Mwende; Motari, Mavyline; Chemutai, Asha; Mapasha, Refilwe Edwin (Elsevier, 2026-10-15)Please read abstract in the article.Item Novel tin dioxide-coated gold and silver nanomaterials for enhanced solar steam generationMakgale, Tshepho Trevor; Diale, M. (Mmantsae Moche) (Wiley, 2026-04-22)Solar steam generation, a technology that harnesses the abundant and clean energy of sunlight, has emerged as a promising solution for global freshwater scarcity. This study explores the potential applications of gold and silver nanostructures coated with tin dioxide and blended to form mixtures to improve photothermal properties for solar steam generation. Transmission electron microscopy was used to successfully confirm the rod-like structures and diverse sizes of the gold and silver nanoparticles, with aspect ratios ranging from 2.2 to 3.3. The collected ultraviolet–visible spectra showed broadened and enhanced light absorption across a range of 350–850 nm. Furthermore, under 1.3511 kW/m2 solar power, solar steam generation efficiencies were found to be 10.87 ± 0.05, 10.71 ± 0.06, and 10.32 ± 0.04% for tin dioxide-based nanofluids, CTAB-based nanofluids, and pure water, respectively. Notably, tin dioxide-based nanofluids also exhibited a higher heat capacity (7734.12 J/°C·Kg) as compared to the CTAB-based nanofluids (7709.25 J/°C·Kg) and pure water (4200 J/°C·Kg), demonstrating its superior thermal management. These results indicate that the strategic blending of tin dioxide encapsulated gold and silver nanorods offers a promising approach to advancing solar energy technologies through improved nanomaterial design.Item Enhancing light absorption in the photoactive layer of organic solar cells using plasmonic copper nanorodsSeimela, Thapelo Ephraim; Hamed, Mohammed S.G.; Diale, M. (Mmantsae Moche) (Wiley, 2026-01)Bulk-heterojunction organic solar cells have brought much interest in renewable energy due to their low cost and large-scale fabrication. Their power conversion efficiency (PCE) suffers due to charge recombination, limiting their commercialization. In this study, the plasmonic resonance of colloidal copper nanorods (CuNRs) has been employed to enhance light absorption inside phenyl-C60-butyric acid methyl ester: poly(3-hexylthiophene) (P3HT:PCBM). The CuNRs with a diameter of 24.63 ± 2.1 nm and length of 53.99 ± 0.57 nm induced transverse and longitudinal absorption peaks at 450 and 680 nm, respectively, inside P3HT:PCBM. The peaks intensify with an increase in the concentration of CuNRs. Photoluminescence spectra showed an improved charge carrier lifetime for P3HT:PCBM with the incorporation of CuNRs. The CuNRs have improved the PCE of ITO/PEDOT:PSS/P3HT:PCBM:CuNRs/LiF/Al device by 34.97%. Incorporating CuNRs in P3HT:PCBM has the potential to improve the PCE of the organic solar cell by inducing plasmonic resonance.Item Defect passivation in CsPbBr3 perovskite using phenethylammonium bromideThubane, Sandile Job; Nombona, Nolwazi; Diale, M. (Mmantsae Moche) (Wiley, 2026-01)Please read abstract in the article.Item Cu:Zn bimetallic nanocomposites as plasmonic enhancers for high-performance thin film organic solar cellsHamed, Mohammed S.G.; Seimela, Thapelo Ephraim; Diale, M. (Mmantsae Moche) (Wiley, 2026-01)Copper-zinc bimetallic nanocomposites (Cu:Zn BMNCs) were synthesized using a wet chemistry and used as an absorber material in thin-film organic solar cells (TFOSCs). The nanocomposites were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and photoluminescence (PL). A traditional device architecture ITO/PEDOT:PSS/P3HT:PCBM-Cu:Zn BMNCs/LiF/Al was used for fabrication. The pristine device, which used a P3HT: PCBM mixture, achieved a PCE of 3.22%. Additionally, adding Cu:Zn BMNCs to the photoactive layer significantly enhanced device performance. The optimal concentration of 1 wt% Cu:Zn BMNCs resulted in a PCE of 5.40%, an increase of over 68% compared to the pristine device. This improvement is attributed to better optical absorption driven by light scattering and localized surface plasmon resonance (LSPR) effects within the absorber layer, which enhances photon harvesting and charge generation. Furthermore, the experiment showed a slight increase in short-circuit current density (Jsc), due to improved charge carrier collection efficiency. These results demonstrate that Cu:Zn BMNCs can enhance both the optical absorption and electrical performance of TFOSCs.Item Analysis of temperature-dependent characteristics of Cr/P-doped Si Schottky barrier diodes before and after 5.4 MeV 241Am irradiationOmotoso, Ezekiel; Meyer, Walter Ernst; Sheppard, Charles J.; Igumbor, Emmanuel; Prinsloo, A.R.E. (Wiley, 2026-01)Please read abstract in the article.Item Highly oriented pyrolytic graphite chemical bonding structure after gallium implantationJafer, Tasabeeh A.O.; Abdelbagi, H.A.A.; Sulyok, A.; Radnóczi, G.Z.; Tőkési, K.; Malherbe, Johan Brand (Nature Research, 2025-11-18)Highly oriented pyrolytic graphite (HOPG) structural changes caused by gallium (Ga) implantation at room temperature were investigated. Ga ions were implanted into HOPG at different energies (10, 20, and 30 keV) and fluences (ranging from 2 × 1015 to 5 × 1016 Ga+/cm2). To monitor structural changes in the samples post-implantation, Raman spectroscopy was employed. The Raman spectra of the pristine HOPG sample displayed low-intensity D peaks at 1359 cm⁻1 and high-intensity G peaks at 1582 cm⁻1. After implantation with 10 keV at a fluence of 5 × 1016 Ga+/cm2, a decrease in G peak intensity was observed, accompanied by an increase in its full width at half maximum (FWHM), indicating defect formation in the HOPG structure. In contrast, implantation with 30 keV at the same fluence (5 × 1016 Ga + /cm2) resulted in the merging of the D and G peaks into a broad peak, signifying the amorphization of HOPG. These results confirm that ion energy plays a significant role in the amorphization of HOPG. Furthermore, implantation with 20 keV Ga ions at fluences ≤ 2 × 1016 Ga+/cm2 introduced some defects in the HOPG structure, while higher fluences (≥ 4 × 1016 Ga+/cm2) led to complete amorphization. After comparing the Raman results with the threshold displacement per atom (dpa) values calculated using the SRIM (Stopping and Range of Ions in Matter) software, it is evident that the HOPG used in this study required a very high dpa (exceeding 35 dpa) for complete amorphization, significantly exceeding the previously suggested range of 0.2 dpa to 3 dpa. The findings of this study align with very few prior results, where no amorphization was observed above 3 dpa. However, further research and testing are necessary to quantify the dpa required for HOPG amorphization.Item Electronic structure calculations on gallium-vacancy defects in Si1-xGexChristopoulos, Stavros-Richard G.; Igumbor, Emmanuel; Mapasha, Refilwe Edwin; Chroneos, Alexander (Nature Research, 2025-11-21)Silicon germanium (Si1 − xGex) has emerged as a mainstream nanoelectronic material and as such its defect processes and energetics are technologically important. In semiconductor alloys the interaction of intrinsic point defects such as vacancies with dopant atoms are critical for the physical properties of the material and impact nanoelectronic device performance. Gallium (Ga) is a p-type dopant in elemental and alloys group IV semiconductors and its interaction with vacancies can impact its diffusion and electronic properties. The gallium-vacancy (GaV) defect pairs are not thoroughly investigated in Si1 − xGex random semiconductor alloys. Here we employ hybrid density functional theory (DFT) to study the electronic properties and binding energies in seven compositions of Si1 − xGex. The prediction of the prevalent GaV pair in each composition is hindered by the large number of local environments that impact in turn the energetics of the defect pairs. To overcome this, we applied the special quasirandom structures (SQS) method and considered the lowest binding energy GaV pairs to the favourable one for every respective composition.Item Novel variational-type method in quantum few-body theoryRakityansky, Sergei Anatoljevich (American Physical Society, 2026-02-17)Please read abstract in the article.Item Thermal annealing effects on the interaction between chromium and silicon carbide in a vacuum environmentThabethe, Thabsile Theodora; Dockrat, Unaisa; Mashabela, Tshegofatso Boys; Kadi, Tshepiso Bridget; Mirzayev, M.N.; Imanova, G.T.; Demir, C.; Maepa, Charity E. (Elsevier, 2025-09)This study examines the morphological, structural, and chemical changes in Cr thin films deposited on SiC substrates and subjected to vacuum annealing at 700 ◦C, 800 ◦C, and 900 ◦C for 2 h. Cr thin films, approximately 250 nm thick, were deposited using the e-beam deposition technique. Post-annealing, additional phases, including chromium carbides and chromium oxides were identified, while Cr3Si persisted as a stable phase across all temperatures. Morphological analysis showed that the as-deposited films were characterized by a uniform surface with finely distributed granules. Annealing at 700 ◦C increased grain size while retaining surface homogeneity. At 800 ◦C and 900 ◦C, the films exhibited significant grain growth and surface roughening, with the roughness increasing from 1.63 nm (as-deposited) to 13.8 nm at 900 ◦C. Additionally, localized segregation and nonhomogeneous surface features emerged at higher temperatures. XRD analysis revealed lattice expansion in the SiC substrate after annealing, indicating structural changes driven by thermal effects. The study highlights the influence of annealing on phase transformations, surface morphology, and structural integrity in Cr/SiC systems. These findings provide a deeper understanding of the thermal behavior of Cr/SiC composites, which is critical for optimizing their performance in high-temperature applications.Item Polymorphic Janus ZrSC monolayer : a first-principles study of structural, mechanical, vibrational, and electronic propertiesOrega, Owen Alfreds; Fwalo, Chewe; Mahapane, Basia David; Mapasha, Refilwe Edwin (Royal Society of Chemistry, 2026-05-20)Two-dimensional Janus materials, characterized by their asymmetric surface composition, offer unique opportunities for tailoring electronic and mechanical properties. Among these, the hypothetical ZrSC monolayer, composed of zirconium sandwiched between sulfur and carbon layers, represents an underexplored system with potential to merge the mechanical durability of carbides with the electronic tunability of chalcogenides. Using first-principles density functional theory (DFT) with van der Waals corrections and Hubbard-U adjustments, we systematically investigate the structural, mechanical, vibrational, and electronic properties of its two polymorphs: the trigonal prismatic 1H and octahedral 1T phases. Our results establish the 1H phase as the thermodynamically stable ground state with a cohesive energy of 6.99 eV per atom, a moderate Young's modulus of 70.7 N m−1, and a tunable semiconductor with an indirect bandgap of 1.63 eV that is highly responsive to mechanical strain. Phonon spectra confirm its dynamical stability, while the 1T phase exhibits significant imaginary frequencies, indicating metastability. Strain engineering induces semiconductor-to-semimetal transitions in the 1H phase, highlighting its potential for flexible electronics and spintronics. We conclude that the 1H ZrSC monolayer is a promising candidate for next-generation 2D devices, offering a versatile platform that bridges mechanical robustness with electronic adaptability, and providing a clear roadmap for experimental synthesis and device integration.Item Optimizing the antimicrobial, antioxidant, and cytotoxic properties of silver nanoparticles synthesized from Elephantorrhiza elephantina (Burch.) extracts : a comprehensive studyMotene, Matshoene V.; Maepa, Charity E.; Sigidi, Muendi T. (MDPI, 2025-03-06)The green synthesis of silver nanoparticles (AgNPs) using Elephantorrhiza elephantina (Burch) bulb extracts and evaluation of their antimicrobial, cytotoxic, and antioxidant properties were investigated. The crude plant extracts were prepared using distilled water, ethanol, and methanol for a comparison. Silver nanoparticles were synthesized and characterized via UV–Visible spectroscopy (UV–VIS), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The formation of silver nanoparticles was confirmed using the UV–VIS spectra at 550 nm. The TEM confirmed the nanoparticle morphology as a mixed dispersed sphere, oval, and triangular shapes with a size range of 7.8 nm to 31.3 nm. The secondary metabolites were detected using TLC, DPPH, and LC-MS. Antimicrobial activity was assessed based on agar-well diffusion; cytotoxicity was examined through MTS assays. Various phytochemical constituents were detected through TLC and LC-MS. The crude extracts and methanol-extract-capped AgNP were able to scavenge free radicals, as shown by the developments of inhibitory bands on the TLC plate. The agar well diffusion test revealed that the AgNP capped methanol extract had potent antimicrobial activity against Gram-positive and Gram-negative multidrug resistant bacteria in comparison with penicillin and neomycin, with inhibition zones ranging between 10 mm and 14 mm for the methanol-extract-capped AgNP. The in vitro MTS assay revealed that methanol crude extracts and methanol-extract-capped AgNP had a less cytotoxic effect on the HEK293 cells in comparison with untreated cells (control). We therefore conclude that methanol was the best reducing solvent with the best overall nanoparticle morphology and performance in antimicrobial and cytotoxicity, in comparison to ethanol and distilled water.Item Visible-light driven photocatalytic degradation of tartrazine using Co@ZIF-8 monolithsTshuma, Piwai; Phiri, Arnold; Chaparadza, Mercy; Seimela, Thapelo Ephraim; Diale, M. (Mmantsae Moche); Poshayi, Nicola Vimbainashe; Marazani, Linia Gedi; Mehlana, Gift (Royal Society of Chemistry, 2026-08-12)Please read abstract in the article.Item Objective clustering protocol for single-molecule data : a lifetime vs. intensity studyLovemore, Michael Andrew Charles; Van Heerden, Bertus; Botha, Joshua Leon; Kruger, T.P.J. (Tjaart) (Elsevier, 2026-06-10)Single-molecule spectroscopy (SMS) is an exceptionally sensitive technique, but its inherently limited photon budget produces noisy data that can readily lead to subjective analyses, fitting errors, and reduced statistical power, obscuring true subpopulations and their dynamics. Here, we present an unbiased, objective method to cluster two-dimensional single-molecule data and demonstrate it on fluorescence lifetime-intensity correlations. The clustering method is based on Gaussian mixture modeling, with the optimal number of clusters determined through information criteria (the Akaike and Bayesian information criteria and integrated completed likelihood) and supplemented by cluster-quality metrics such as average cluster tightness and the fraction of points outside confidence ellipses, which guide the selection of statistically robust and physically meaningful clusters. The protocol was benchmarked on simulated datasets spanning clean, smeared, and noisy overlap-limited regimes and applied to experimental data from Alexa Fluor 647 and QD605. This approach reliably recovers relevant subpopulations even in the presence of noise and overlapping distributions, providing an objective framework for analyzing single-molecule heterogeneity, with limitations arising primarily under severe geometric overlap or extreme state-occupancy imbalance where distinct populations are no longer separable.Item Size-dependent fluorescence kinetics reveal contributions of intrinsic quenching and singlet–triplet annihilation during LHCII aggregationConradie, Francois; Van Heerden, Bertus; Gwizdala, Michal; Kruger, T.P.J. (Tjaart) (Elsevier, 2026-11-01)Aggregation of the main antenna complex of higher plants, Light-Harvesting Complex II (LHCII), is widely used as an in-vitro model for energy-dependent quenching (qE), yet fluorescence reduction in aggregates is frequently interpreted without a quantitative separation of intrinsic quenching from excitation-induced annihilation. Here, we address this ambiguity by directly correlating aggregate size, concentration, steady-state fluorescence intensity, and decay kinetics during controlled, incremental aggregation of isolated LHCII. By combining fluorescence correlation spectroscopy (FCS) with time-correlated single-photon counting (TCSPC) in a unified experimental framework, we monitored structural and photophysical changes in real time as detergent removal drives biphasic aggregation. We quantified the aggregate composition from the particle concentrations, enabling direct scaling of the absorption cross-section with aggregate size. The average fluorescence lifetime decreased semi-logarithmically with increases in hydrodynamic radius, whereas steady-state fluorescence intensities deviated strongly from this trend. Intensity-dependent measurements and steady-state kinetic modeling reveal that singlet-triplet annihilation (STA) emerges at moderate excitation intensities and rapidly becomes the dominant contributor to fluorescence quenching, even for relatively small aggregates. In contrast, intrinsic quenching increases more gradually with aggregate size. By quantitatively disentangling intrinsic excitation quenching from annihilation processes, this work demonstrates that STA can govern the apparent photophysical response of aggregated LHCII across excitation regimes commonly considered non-annihilating. The size-dependent mechanistic framework presented here provides a basis for distinguishing intrinsic quenching from annihilation effects in aggregation-based studies of photosynthetic antenna complexes. HIGHLIGHTS • TCSPC-FCS uncovers biphasic LHCII aggregation during detergent removal. • Average LHCII aggregate compositions can be estimated from relative particle concentrations. • Excitation quenching depends logarithmically on LHCII aggregate size. • LHCII aggregation dramatically increases singlet-triplet annihilation. • Quenching and annihilation in LHCII aggregates can be disentangled by incremental aggregation.Item Synergetic properties of advanced materials for high-power and high-temperature applicationsMengesha, Wubshet Getachew; Nagessar, Kaveer (Springer Nature, 2026-04-10)This paper explores the advancements, applications, and challenges of advanced thermal and magnetic materials in high-power and high-temperature environments. These materials, including high-temperature superconductors, ferromagnetic materials, and magnetic alloys, are crucial for industries such as energy, aerospace, automotive, and electronics. They are crucial for managing heat, converting energy, and storing it, which boosts the efficiency and dependability of renewable energy systems, electric vehicles, and aerospace technologies. Nonetheless, they encounter major obstacles, such as material breakdown under harsh conditions, expensive production, and sustain- ability issues. The study explores essential thermal properties like heat capacity, thermal conductivity, thermal expansion, and thermal stress, highlighting the significance of ceramics, composites, metals, carbon nanotubes, and phase-change materials. It also investigates magnetic properties like permeability, coercivity, and remanence, essential for high-power applications. Emerging technologies such as nanotechnology, additive manufacturing, and machine learning offer promising solutions to overcome existing limitations. The review highlights the need for interdisciplinary research to develop sustainable and cost-effective materials capable of withstanding extreme conditions while maintaining performance. It underscores the importance of continuing research and development to address global energy and environmental challenges, paving the way for next-generation technologies. In summary, cutting-edge thermal and magnetic materials are set to transform industries, paving the way for more efficient and dependable technological advancements.Item Enhanced performance of PTB7-Th:PCBM-based organic solar cells via broadening of localized surface plasmon resonanceMulat, Simenew A.; Hamed, Mohamed S.G.; Hone, Fekadu G.; Nchinda, Leonato Tambua; Gelderblom, Elizabeth M.; Diale, M. (Mmantsae Moche); Kruger, T.P.J. (Tjaart); Bekri, Nika; Tegegne, Newayemedhin A. (Royal Society of Chemistry, 2026-07)Please read abstract in the article.