Radiation-Induced Synthesis and Superparamagnetic Properties of Ferrite Fe3O4 Nanoparticles.

Ultra-small magnetic Fe3O4 nanoparticles are successfully synthesized in basic solutions by using the radiolytic method of the partial reduction in FeIII in the presence of poly-acrylate (PA), or by using the coprecipitation method of FeIII and FeII salts in the presence of PA. The optical, structural, and magnetic properties of the nanoparticles were examined using UV-Vis absorption spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and SQUID magnetization measurements. The HRTEM and XRD analysis confirmed the formation of ultra-small magnetite nanoparticles in a spinel structure, with a smaller size for radiation-induced particles coated by PA (5.2 nm) than for coprecipitated PA-coated nanoparticles (11 nm). From magnetization measurements, it is shown that the nanoparticles are superparamagnetic at room temperature. The magnetization saturation value Ms = 50.1 A m2 kg-1 of radiation-induced nanoparticles at 60 kGy is higher than Ms = 18.2 A m2 kg-1 for coprecipitated nanoparticles. Both values are compared with nanoparticles coated with other stabilizers in the literature.

Overlooked Activation Role of Sulfite in Accelerating Hydrated Electron Treatment of Perfluorosulfonates.

Photoexcitation of sulfite (SO32-) is often used to generate hydrated electrons (eaq-) in processes to degrade perfluoroalkyl and polyfluoroalkyl substances (PFASs). Conventional consensus discourages the utilization of SO32- concentrations exceeding 10 mM for effective defluorination. This has hindered our understanding of SO32- chemistry beyond its electron photogeneration properties. In contrast, the radiation-chemical study presented here, directly producing eaq- through water radiolysis, suggests that SO32- plays a previously overlooked activation role in the defluorination. Quantitative 60Co gamma irradiation experiments indicate that the increased SO32- concentration from 0.1 to 1 M enhances the defluorination rate by a remarkable 15-fold, especially for short-chain perfluoroalkyl sulfonate (PFSA). Furthermore, during the treatment of long-chain PFSA (C8F17-SO3-) with a higher concentration of SO32-, the intermediates of C8H17-SO3- and C3F7-COO- were observed, which are absent without SO32-. These observations highlight that a higher concentration of SO32- facilitates both reaction pathways: chain shortening and H/F exchange. Pulse radiolysis measurements show that elevated SO32- concentrations accelerate the bimolecular reaction between eaq- and PFSA by 2 orders of magnitude. 19F NMR measurements and theoretical simulations reveal the noncovalent interactions between SO32- and F atoms, which exceptionally reduce the C-F bond dissociation energy by nearly 40%. As a result, our study offers a more effective strategy for degrading highly persistent PFSA contaminants.

Media coverage of COVID-19 vaccines: sources of information, and verification practices of journalists in Ghana.

BACKGROUND: Research on vaccines confirms the crucial role media play in framing discourses and mobilizing public support for successful immunization campaigns. What journalists cover on vaccination issues and their diligence in producing stories can influence attitudes to and uptake of vaccines. This paper contributes to emerging discussions on the role of the media in pandemics and in vaccination programs by interrogating the information seeking and verification practices of journalists reporting on COVID-19 vaccines in Ghana. METHODS: A cross-sectional online survey was conducted among journalists from June to July 2021 through self-administered questionnaires by means of Google forms. The opinions of 300 respondents, randomly drawn from members of the Ghana Journalists' Association, were solicited and a response rate of 73% obtained. RESULTS: Majority of journalists surveyed relied on official health sources for their information on COVID-19 vaccines (61.5%) and were confident the benefits of vaccines outweigh the risks (70%). While journalists relied on a variety of expert sources, social media platforms served as important sources of information also, with respondents stating a preference for Facebook (48.3%), and WhatsApp (44%). Journalists stated they were guided by sound practices such as source credibility and relevance, but betrayed weaknesses in their verification practices with a third of them admitting to sharing unsolicited information from social media. CONCLUSIONS: Journalists in Ghana generally display a positive attitude towards COVID-19 vaccines and regularly search for information from official sources to inform their work, thus making them vital allies in overcoming vaccine hesitancy. Laxity in verification practices, however, makes them inadvertent agents of misinformation.

Unveiling the Intimate Mechanism of the Crocin Antioxidant Properties by Radiolytic Analysis and Molecular Simulations.

The successive steps of the oxidation mechanism of crocin, a major compound of saffron, by the free OH• radical are investigated by pulse radiolysis, steady-state (gamma) radiolysis methods, and molecular simulations. The optical absorption properties of the transient species and their reaction rate constants are determined. The absorption spectrum of the oxidized radical of crocin resulting from the H-abstraction presents a maximum of 678 nm and a band of 441 nm, almost as intense as that of crocin. The spectrum of the covalent dimer of this radical contains an intense band at 441 nm and a weaker band at 330 nm. The final oxidized crocin, issued from radical disproportionation, absorbs weaker with a maximum of 330 nm. The molecular simulation results suggest that the OH• radical is electrostatically attracted by the terminal sugar and is scavenged predominantly by the neighbor methyl site of the polyene chain as in a sugar-driven mechanism. Based on detailed experimental and theoretical investigations, the antioxidant properties of crocin are highlighted.

Pathways of the Dissociative Electron Attachment Observed in 5- and 6-Azidomethyluracil Nucleosides: Nitrogen (N2) Elimination vs Azide Anion (N3-) Elimination.

5-Azidomethyl-2'-deoxyuridine (5-AmdU, 1) has been successfully employed for the metabolic labeling of DNA and fluorescent imaging of live cells. 5-AmdU also demonstrated significant radiosensitization in breast cancer cells via site-specific nitrogen-centered radical (π-aminyl (U-5-CH2-NH•), 2, and σ-iminyl (U-5-CH═N•), 3) formation. This work shows that these nitrogen-centered radicals are not formed via the reduction of the azido group in 6-azidomethyluridine (6-AmU, 4). Radical assignments were performed using electron spin resonance (ESR) in supercooled solutions, pulse radiolysis in aqueous solutions, and theoretical (DFT) calculations. Radiation-produced electron addition to 4 leads to the facile N3- loss, forming a stable neutral C-centered allylic radical (U-6-CH2•, 5) through dissociative electron attachment (DEA) via the transient negative ion, TNI (U-6-CH2-N3•-), in agreement with DFT calculations. In contrast, TNI (U-5-CH2-N3•-) of 1, via facile N2 loss (DEA) and protonation from the surrounding water, forms radical 2. Subsequently, 2 undergoes rapid H-atom abstraction from 1 and produces the metastable intermediate α-azidoalkyl radical (U-5-CH•-N3). U-5-CH•-N3 converts facilely to radical 3. N3- loss from U-6-CH2-N3•- is thermodynamically controlled, whereas N2 loss from U-5-CH2-N3•- is dictated by protonation from the surrounding waters and resonance conjugation of the azidomethyl side chain at C5 with the pyrimidine ring.

Application of Geant4-DNA for simulating water radiolysis induced by Auger electron-emitting radionuclides.

Auger-emitting radionuclides have potential application in targeted radiotherapy, particularly for metastatic cancers. This possibility, especially, is stemmed from their characteristic short-range (a few µm) in biological systems allowing localization of high dose within small tumours. To explore this potential application, a Geant4 Monte Carlo toolkit has been employed to simulate the energy deposition of different radionuclides in a water model. The Geant4 Monte Carlo toolkit has model packages to simulate the interaction of radiation with matter and with diverse applications such as studies in science and medicine. In this study, the Geant4-DNA package was used to simulate the radiolytic yields induced by some Auger electron-emitting (AE) radionuclides including; I-131, I-125 and Pd-103, In-111, Ru-97 and Rh-103 m in water model. The results showed that the transient yield of the radiolytic species is characterized by the kinetic energies of the emitted electrons. It was observed that almost all the radionuclides, except I-131, deposited more energy in their proximity thereby inducing a high density of spurs to interact in a short time. It is, therefore, important to consider the kinetic energies of the emitted particles in choosing a radionuclide for specified targeted radiotherapy. This means that apart from their toxicity, compatibility with chelator and carrier molecules, and method of production, we can predict radionuclides such as In-111, Ru-97, Pb-103 m and I-125 could be relevant for targeted radiotherapy for the treatment of metastasis lesions, or tiny tumours at the cellular level, and tumours after surgical resection.

Association of dietary calcium, magnesium, sodium, and potassium intake and hypertension: a study on an 8-year dietary intake data from the National Health and Nutrition Examination Survey.

BACKGROUND/OBJECTIVES: There has been an increased interest in determining calcium magnesium, sodium, and potassium's distinct effects on hypertension over the past decade, yet they simultaneously regulate blood pressure. We aimed at examining the association of dietary calcium, magnesium, sodium, and potassium independently and jointly with hypertension using National Health and Nutrition Examination Survey data from 2007 to 2014. MATERIALS/METHODS: The associations were examined on a large cross-sectional study involving 16684 US adults aged>20 years, using multivariate analyses with logistical models. RESULTS: Sodium and calcium quartiles assessed alone were not associated with hypertension. Potassium was negatively associated with hypertension in the highest quartile, 0.64 (95% confidence interval [CI], 0.48-0.87). When jointly assessed using the high and low cut-off points, low sodium and corresponding high calcium, magnesium, and potassium intake somewhat reduced the odds of hypertension 0.39 (95% CI, 0.20-0.76). The sodium-to-potassium ratio was positively associated with hypertension in the highest quartile1.50 (95% CI, 1.11-2.02). When potassium was adjusted for sodium intake and sodium-to-potassium ratio assessed among women, increased odds of hypertension were reported in the highest quartile as 2.02 (95% CI, 1.18-3.34) and 1.69 (95% CI, 1.12-2.57), respectively. The association of combined minerals on hypertension using dietary goals established that men meeting the reference intakes for calcium and exceeding for magnesium had reduced odds of hypertension 0.51 (95% CI, 0.30-0.89). Women exceeding the recommendations for both calcium and magnesium had the lower reduced odds of 0.30 (95% CI, 0.10-0.69). CONCLUSIONS: Our results suggest that the studied minerals' association on hypertension is stronger when jointly assessed, mostly after gender stratification. As compared to men, women increased their risk of hypertension even with a low sodium intake. Women would also reasonably reduce their risk of developing hypertension by increasing calcium and magnesium intake. In comparison, men would somewhat be protected from developing hypertension with calcium intake meeting the dietary goals and magnesium exceeding the nutritional goals.

Oxidation of Silver Cyanide Ag(CN)2- by the OH Radical: From Ab Initio Calculation to Molecular Simulation and to Experiment.

We investigate the oxidation of silver cyanide AgI(CN)2- in water by the OH radical in order to compare this complex with the free cation Ag+ and to measure the influence of the ligands. High-level ab initio calculations of the model species AgII(CN)2· enable the calibration of molecular simulations and the prediction of the oxidized species: AgII(CN)2(H2O)2· and its absorption spectrum, with an intense band at 292 nm and a weaker one at 390 nm. Pulse radiolysis measurements of the oxidation of AgI(CN)2- by the OH radical in water yields a transient species with a broad, intense band at 290 nm and a weaker band at 410 nm at short times after the pulse and a blue shift of the spectrum at longer times. The prediction of the simulations, that the oxidized complex AgII(CN)2(H2O)2· is formed, is confirmed by thermochemistry. Our calculations also suggest that the formation of the OH-adduct is possible only in very basic solution and that the blue shift observed at long times after the pulse is due to disproportionation of the oxidized complex. We also perform molecular simulations of the oxidation of free Ag+ cations by the OH radical. The results are compared to that of the literature and to the results obtained with the AgI(CN)2- complex.

Predictors of underweight in children under-five years in Ghana.

BACKGROUND: Underweight is a key indicator of malnutrition in children and results in long term effects such as abnormalities in physical and mental health, behavioural problems, and low educational achievement. OBJECTIVE: Using the conceptual framework for child malnutrition by the United Nations Children's Fund, we examined the predictors of underweight in children under five years in Ghana. METHODS: This cross-sectional study made use of data from the 2014 Ghana Demographic and Health Survey. A total of 2720 children were included in the analysis. Descriptive and inferential statistics comprising frequency, percentage, chi-square, and binary logistic regression were used in analysing the data. RESULTS: The prevalence of underweight was 11%. Age, wealth status, mother's education, region, ethnicity, household toilet facility, the source of drinking water, the incidence of diarrhoea, and subscription to health insurance significantly predicted underweight in the children. The risk of being underweight was higher in females than males (OR=1.04, 95% CI=0.81-1.34). This was, however, not statistically significant. The probability of being underweight also declined significantly with mother's level of education. CONCLUSION: Our findings underscore the need for the Ghana Health Service and other health sector stakeholders to apportion interventions with a focus on improving complementary feeding, poverty alleviation, and health status of children. FUNDING: No funding was received for the study.

A Compact "Water Window" Microscope with 60 nm Spatial Resolution for Applications in Biology and Nanotechnology.

Short illumination wavelength allows an extension of the diffraction limit toward nanometer scale; thus, improving spatial resolution in optical systems. Soft X-ray (SXR) radiation, from "water window" spectral range, λ=2.3-4.4 nm wavelength, which is particularly suitable for biological imaging due to natural optical contrast provides better spatial resolution than one obtained with visible light microscopes. The high contrast in the "water window" is obtained because of selective radiation absorption by carbon and water, which are constituents of the biological samples. The development of SXR microscopes permits the visualization of features on the nanometer scale, but often with a tradeoff, which can be seen between the exposure time and the size and complexity of the microscopes. Thus, herein, we present a desk-top system, which overcomes the already mentioned limitations and is capable of resolving 60 nm features with very short exposure time. Even though the system is in its initial stage of development, we present different applications of the system for biology and nanotechnology. Construction of the microscope with recently acquired images of various samples will be presented and discussed. Such a high resolution imaging system represents an interesting solution for biomedical, material science, and nanotechnology applications.