Ferrites have a plethora of applications in the myriad fields of technology. Ferrites are widely used in conventional electronic, electrical, and magnetic devices. For the past two decades, since the ...discovery of the superparamagnetic nature of nanostructured ferrites, their applications in biotechnology and biomedical sciences as well as in advanced electronics and microwave devices have gained immense attention. In this review, the historical development of ferrite science and technology, and the synthesis methods for ferrite nanoparticle preparation and their applications have been discussed. Various synthetic methods with typical examples, their advantages as well as limitations have been discussed in details. Traditional industrial applications of various ferrites have also been discussed citing relevant patents. Recent developments on nanoferrite research in terms of synthetic methods as well as advanced applications have been discussed elaborately.
Context. Extreme solar activity fluctuations and the occurrence of solar grand minima and maxima episodes, such as the Maunder minimum and Medieval maximum are well-established, observed features of ...the solar cycle. Nevertheless, such extreme activity fluctuations and the dynamics of the solar cycle during Maunder minima-like episodes remain ill understood. Aims. We explore the origin of such extreme solar activity fluctuations and the role of dual poloidal field sources, namely the Babcock-Leighton mechanism and the mean-field α effect in the dynamics of the solar cycle. We mainly concentrate on entry and recovery from grand minima episodes such as the Maunder minimum and the dynamics of the solar cycle, including the structure of solar butterfly diagrams during grand minima episodes. Methods. We use a kinematic solar dynamo model with a novel set-up in which stochastic perturbations force two different poloidal sources. We explore different regimes of operation of these poloidal sources with distinct operating thresholds to identify the importance of each. The perturbations are implemented independently in both hemispheres which allows the study of the level of hemispheric coupling and hemispheric asymmetry in the emergence of sunspots. Results. From the simulations performed we identify a few different ways in which the dynamo can enter a grand minima episode. While fluctuations in any of the α effects can trigger intermittency, in keeping with results from a mathematical time-delay model we find that the mean-field α effect is crucial for the recovery of the solar cycle from a grand minima episode, which a Babcock-Leighton source alone fails to achieve. Our simulations also demonstrate many types of hemispheric asymmetries, including grand minima and failed grand minima where only one hemisphere enters a quiescent state. Conclusions. We conclude that stochastic fluctuations in two interacting poloidal field sources working with distinct operating thresholds is a viable candidate for triggering episodes of extreme solar activity and that the mean-field α effect capable of working on weak, sub-equipartition fields is critical to the recovery of the solar cycle following an extended solar minimum. Based on our results, we also postulate that solar activity can exhibit significant parity shifts and hemispheric asymmetry, including phases when only one hemisphere is completely quiescent while the other remains active, to, successful grand minima like conditions in both hemispheres.
Two of the most widely used electronic-structure theory methods, namely, Hartree–Fock and Kohn–Sham density functional theory, require the iterative solution of a set of Schrödinger-like equations. ...The speed of convergence of such a process depends on the complexity of the system under investigation, the self-consistent-field algorithm employed, and the initial guess for the density matrix. An initial density matrix close to the ground-state matrix will effectively allow one to cut out many of the self-consistent steps necessary to achieve convergence. Here, we predict the density matrix of Kohn–Sham density functional theory by constructing a neural network that uses only the atomic positions as information. Such a neural network provides an initial guess for the density matrix far superior to that of any other recipes available. Furthermore, the quality of such a neural-network density matrix is good enough for the evaluation of interatomic forces. This allows us to run accelerated ab initio molecular dynamics with little to no self-consistent steps.
Objective:
This study was designed to establish the reliability of neurologic examination, neuron‐specific enolase (NSE), and median nerve somatosensory‐evoked potentials (SEPs) to predict poor ...outcome in patients treated with mild hypothermia after cardiopulmonary resuscitation (CPR).
Methods:
This multicenter prospective cohort study included adult comatose patients admitted to the intensive care unit (ICU) after CPR and treated with hypothermia (32–34°C). False‐positive rates (FPRs 1 − specificity) with their 95% confidence intervals (CIs) were calculated for pupillary light responses, corneal reflexes, and motor scores 72 hours after CPR; NSE levels at admission, 12 hours after reaching target temperature, and 36 hours and 48 hours after collapse; and SEPs during hypothermia and after rewarming. The primary outcome was poor outcome, defined as death, vegetative state, or severe disability (Glasgow Outcome Scale 1–3) after 6 months.
Results:
Of 391 patients included, 53% had a poor outcome. Absent pupillary light responses (FPR 1; 95% CI, 0–7) or absent corneal reflexes (FPR 4; 95% CI, 1–13) 72 hours after CPR, and absent SEPs during hypothermia (FPR 3; 95% CI, 1–7) and after rewarming (FPR 0; 95% CI, 0–18) were reliable predictors. Motor scores 72 hours after CPR (FPR 10; 95% CI, 6–16) and NSE levels were not.
Interpretation:
In patients with persisting coma after CPR and therapeutic hypothermia, use of motor score or NSE, as recommended in current guidelines, could possibly lead to inappropriate withdrawal of treatment. Poor outcomes can reliably be predicted by testing brainstem reflexes 72 hours after CPR and performing SEP. ANN NEUROL 2012;71:206–212
Formation of 2D-networked structures of disk-like islands for ultrathin Langmuir–Schaefer (LS) films of thiol-coated Au-nanoparticles (DT-AuNPs) on H-passivated Si substrates is evidenced for the ...first time, directly from a broad peak in grazing incidence small angle X-ray scattering data and also from atomic force microscopy images. Theoretical modeling of the system, carried out based on density–density and height–height correlation functions, supports well the formation of such structures. The structural information of the LS films, obtained at different surface pressure, helps to infer the growth of Langmuir monolayers of DT-AuNPs, which is very important in understanding the self-assembly process of nanoparticles at the air–water interface and in controlling the growth of 2D-networked nanostructures in large areas. On the surface of water, DT-AuNPs first self-assembled around different points to form disk-like islands of nanometer size and monolayer height, due to the complex balance of long range van der Waals attractions and short-range steric repulsion of the DT-AuNPs, initiated by solvent evaporation and also to optimize the hydrophobic repulsive force of water. On barrier compression, the size and 2D-network of the islands grow due to a combined effect of collision induced coalescence and solid-like behavior resisting deformation of the islands. On the other hand, the separation between the DT-AuNPs either decreases or increases depending upon the competitive effects of packing or buckling.
•Carbon black-ethylene glycol (CB-EG) nanofluids were investigated.•Extinction coefficient increased linearly with CB concentration within 450–820 nm.•An enhancement of overall photo-thermal ...efficiency of 27.43% was obtained.•Local photo-thermal efficiency improves with concentration and depth of fluid.
Direct absorption solar collector (DASC) is a promising method of harvesting solar energy. Present work considers carbon black-ethylene glycol (CB-EG) based nanofluids as the working fluids for DASC applications. Nanofluids were synthesized by the two-step method. Various studies carried out in this work include long time homogeneity, energy absorption characteristic and transient temperature profiles as functions of fluid thickness, light exposure time and concentration of the nanoparticles. Improved absorption characteristics, compared with those of the base fluid, towards incident irradiance were observed in all cases. About 27.90% increment in overall photo-thermal conversion efficiency over that of the ethylene glycol (EG) alone is observed for the case of 15 ppm carbon black (CB) concentration with an exposure time of 1200 s. Measured data show increasing trends in local photo-thermal efficiency with the thickness of the liquid layer as well as with the concentration of the suspended nanoparticles. These studies confirm that CB-EG based nanofluids can be used as potential working fluids for DASCs.
The study was undertaken to establish the role of novel mutations within AdeRS (regulator of efflux pump AdeABC) associated with overexpression of AdeABC, hence cause carbapenem resistance among ...Acinetobacter baumannii. In addition, the study was designed to understand the possible atomic level interactions between carbapenems with AdeABC and molecular mechanism of efflux pump inhibition by PAβN (Efflux pump Inhibitor).
MIC of carbapenems was checked with and without PAβN among A. baumannii (n=56) causing neonatal septicaemia. Overexpression of AdeABC was determined by q-RT PCR. Mutations within AdeRS was determined by sequencing and their role was established using predictive modelling based 3D structure analysis. Protein-substrate interaction studies were performed using molecular docking to understand the binding pattern of FDA approved carbapenems and PAβN in three binding sites (periplasmic, proximal, distal) of AdeB.
Exposure of the carbapenem-resistant A. baumannii (CRABs) to PAβN resulted in a decrease in the MICs of carbapnems among 39% of isolates (15/38). Overall, 29% (11/38) of CRAB showed overexpression of AdeB. Mutations within AdeS (GLY186VAL, SER188PHE, GLU121LYS, VAL255ILE) and AdeR (VAL120ILE, ALA136VAL) were detected among which three novel mutations (GLY186VAL, SER188PHE, GLU121LYS) were found to be associated with overexpression of AdeABC established by homology modelling. Our study mechanistically shows how these mutations prevent the phospho-transfer to AdeR which inhibit the binding of AdeR to the Inter Cistronic Space and hence, cause overexpression of efflux pump. Moreover, molecular docking indicates less binding of carbapenems and PAβN at distal site as compared to other sites. However, PAβN was found to block the carbapenem interacting residues in AdeB which indicates its role as a competitive inhibitor of AdeB substrates.
Novel mutations within AdeRS are reported for the first time along with their role in AdeB overexpression using predictive 3D modelling. In addition, the study is first time reporting the illustrative demonstration of molecular interaction between AdeB, carbapenems and PAβN. This study revealed the key residues of AdeB that interact with carbapenems as well as PAβN that helping us to understand the molecular reasoning of inhibition as well as creating a future platform for designing novel inhibitors.
Palladium nanoparticles were synthesized by employing Polyol solution chemistry technique. In this method ethylene glycol was used to reduce sodium tetrachloropalladate at 100°C in presence of ...polyvinylpyrrolidone (PVP) to yield ∼10nm sized particles, which was confirmed by transmission electron microscopy (TEM) studies. Thin films of the synthesized nanoparticles on glass substrates were characterized by glancing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM) to check crystallinity and surface morphology, respectively. Both TEM and GIXRD results support the faceted geometry of nanoparticles. Resistive sensor devices were fabricated with palladium films on glass substrates by laying fine silver paste lines in the form of interdigitated fingers. The hydrogen sensor studies at different temperatures (35–75°C) with gas concentrations (0.1–1%) in nitrogen revealed a dual response trend. The device resistance increased slightly and then decreased sharply upon exposure to hydrogen in nitrogen. Optimum response was obtained at 50°C, with response time (t90) of 3s in 1000ppm hydrogen in nitrogen. Similar studies in air showed only increase in resistance. The data reveal the decrease in response time with the decrease in hydrogen concentration, which is an optimistic result from application viewpoint. Detailed analysis of the results along with the selectivity studies has been presented.
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