Doping Independent Work Function and Stable Band Gap of Spinel Ferrites with Tunable Plasmonic and Magnetic Properties

Tuning optical or magnetic properties of nanoparticles, by addition of impurities, for specific applications is usually achieved at the cost of band gap and work function reduction. Additionally, conventional strategies to develop nanoparticles with a large band gap also encounter problems of phase separation and poor crystallinity at high alloying degree. Addressing the aforementioned trade-offs, here we report Ni–Zn nanoferrites with energy band gap (Eg) of ≈3.20 eV and a work function of ≈5.88 eV. While changes in the magnetoplasmonic properties of the Ni–Zn ferrite were successfully achieved with the incorporation of bismuth ions at different concentrations, there was no alteration of the band gap and work function in the developed Ni–Zn ferrite. This suggests that with the addition of minute impurities to ferrites, independent of their changes in the band gap and work function, one can tune their magnetic and optical properties, which is desired in a wide range of applications such as nanobiosensing, nanoparticle based catalysis, and renewable energy generation using nanotechnology

Orientation Sensitivity at Different Stages of Object Processing: Evidence from Repetition Priming and Naming

An ongoing debate in the object recognition literature centers on whether the shape representations used in recognition are coded in an orientation-dependent or orientation-invariant manner. In this study, we asked whether the nature of the object representation (orientation-dependent vs orientation-invariant) depends on the information-processing stages tapped by the task

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Effect of gadolinium on magnetic circular dichroism and electron magnetic resonance of ε-Fe2O3 nanoparticles formed in borate glasses

A remarkable characteristic of borate glasses is the ability of forming magnetic nanoparticles at low doping with transition element oxides. We have studied structure and magnetic properties of iron oxide nanoparticles formed in borate glasses, in particular, concentration and temperature dependences of magnetic circular dichroism (MCD) and electron magnetic resonance (EMR) spectra. A series of glasses of molar composition 22.5K 2 O-22.5Al 2 O 3-55B 2 O 3 doped with 1.5 mass % of Fe 2 O 3 and different contents of Gd 2 O 3 from 0.1 to 1.0 mass % was prepared using a conventional melt quenching technique and subjected to an additional thermal treatment. The whole set of results allows to identify the predominant magnetic phase in these glasses as ε-Fe 2 O 3 nanoparticles, with a considerable part of iron ions substituted by gadolinium. Analysis and computer simulations of the EMR spectra allow separating the contribution of electron paramagnetic resonance of diluted iron ions and together with the temperature dependences of magnetization demonstrate a superparamagnetic character of the nano-particle magnetism

Formation and evolution of magnetic nanoparticles in borate glass simultaneously doped with Fe and Mn oxides

Evolution of the phase state of paramagnetic additions at various stages of synthesis and subsequent thermal treatment of glasses of the system Al2O3-K2O-B2O3 simultaneously doped with Fe2O3 and MnO is studied by means of a combination of experimental techniques: Faraday rotation (FR), electron magnetic resonance (EMR), transmission electron microscopy (TEM), Mössbauer spectroscopy, and magnetic measurements. Both FR and EMR show that magnetically ordered clusters occur already at the first stage of the glass preparation. In particular, for the ratio of the Fe and Mn oxides in the charge close to 3:2, fine magnetic nanoparticles are formed with characteristics similar to those of manganese ferrite. By computer simulating the EMR spectra at variable temperatures, a superparamagnetic nature of these nanoparticles is confirmed and their mean diameter is estimated as approximately 3.2 nm. In the thermally treated glasses larger magnetic nanoparticles are formed, giving rise to FR spectra, characteristic of magnetically ordered systems, and the EMR spectra different from those in as-prepared glasses but also showing superparamagnetic narrowing. The Mössbauer spectroscopy corroborates the manganese ferrite structure of the nanoparticles and indicates their coexistence in the ferrimagnetic and superparamagnetic states. The TEM shows the presence of polydisperse nanoparticles on the background of the glass matrix, and electron diffraction of a selected region containing larger particles indicates a crystal structure close to that of MnFe2O4. Energy-dispersive atomic x-ray spectra confirm that the major part of Fe and Mn introduced to the glass composition is gathered in the particles, with the concentration ratio close to 2:1, characteristic of bulk MnFe2O4. Magnetic hysteresis loops of samples subjected to an additional thermal treatment demonstrate a strong increase in the coercive force, remnant magnetization, and high-field magnetic susceptibility with temperature decrease. The consistent results obtained using various techniques demonstrate that the formation of nanoparticles with characteristics close to those of MnFe2O4 confers to these glasses magnetic and magneto-optical properties typical of substances possessing magnetic order

Сравнительное изучение -Fe2O3 и ϵ-Fe2O3 наночастиц, формирующихся в стекле, допированном железом и гадолинием

Formation and properties of the iron oxides -Fe2O3 and ϵ-Fe2O3 nanoparticles arising in glasses of basic compositions Ge2O-K2O-Al2O3-B2O3 and K2O-Al2O3-B2O3 doped with different concentrations of Fe2O3 and Gd2O3 and subjected to the additional thermal treatment are studied. The X-ray diffraction, TEM microscopy, magnetooptical effects, and electron spin resonance study allow elucidating the matrix and Gd role in determining the nanoparticle propertiesИзучены свойства наночастиц -Fe2O3 и ϵ-Fe2O3, формирующихся в стеклах основного состава Ge2O-K2O-Al2O3-B2O3 и K2O-Al2O3-B2O3, допированных Fe2O3 и Gd2O3 и подвергнутых дополни- тельной термической обработке. Результаты исследования рентгеновской дифракции, электрон- ной микроскопии, магнитооптических эффектов и электронного спинового резонанса позволили объяснить роль матрицы и гадолиния в определении свойств наночасти

Сравнительное изучение -Fe2O3 и ϵ-Fe2O3 наночастиц, формирующихся в стекле, допированном железом и гадолинием

Formation and properties of the iron oxides -Fe2O3 and ϵ-Fe2O3 nanoparticles arising in glasses of basic compositions Ge2O-K2O-Al2O3-B2O3 and K2O-Al2O3-B2O3 doped with different concentrations of Fe2O3 and Gd2O3 and subjected to the additional thermal treatment are studied. The X-ray diffraction, TEM microscopy, magnetooptical effects, and electron spin resonance study allow elucidating the matrix and Gd role in determining the nanoparticle propertiesИзучены свойства наночастиц -Fe2O3 и ϵ-Fe2O3, формирующихся в стеклах основного состава Ge2O-K2O-Al2O3-B2O3 и K2O-Al2O3-B2O3, допированных Fe2O3 и Gd2O3 и подвергнутых дополни- тельной термической обработке. Результаты исследования рентгеновской дифракции, электрон- ной микроскопии, магнитооптических эффектов и электронного спинового резонанса позволили объяснить роль матрицы и гадолиния в определении свойств наночасти