Lantana camara berry for the synthesis of silver nanoparticles

Objective:To synthesize the silver nunoparticles(AgNPs) by reduction of silver ions into nano silver,using ripened berry extract of Lantana camara and evaluate its antioxidant activity against 1.1-diphenyl-2- picrylhydrazyl.Methods:The prepared AgNPs were characterized by visual,UV-visible spectrophotometer.dynamic light scattering and transmission electron microscopy with selected area electron diffraction.Results:Transmission electron microscopy and dynamic light scattering analysis confirmed the AgNPs are spherical and 75.2 nm average sized.Selected area electron diffraction analysis supports that the obtained nanoparticles were in crystalline form.In addition,the antioxidant efficacy of prepared AgNPs was found to be higher than berry extract against 1.1-diphenyl-2-picrylhydrazyl.Conclusions:From the results obtained it is suggested that surface modified AgNPs at lower concentration,showed higher antioxidant activity than berry extract against 1,1-diphenyl-2-picrylhydrazyl and could be used effectively in future ethno pharmacological concerns.

A study of the relation between intensity oscillations and magnetic field parameters in a sunspot: Hinode observations

We present properties of intensity oscillations of a sunspot in the photo- sphere and chromosphere using G band and Ca u H filtergrams from Hinode. Intensity power maps as function of magnetic field strength and frequency reveal reduction of power in the G band with an increase in photospheric magnetic field strength at all frequencies. In Ca II H, however, stronger fields exhibit more power at high frequen- cies, particularly in the 4.5-8.0 mHz band. Power distributions in different locations of the active region show that the oscillations in Ca II H exhibit more power compared to that of the G band. We also relate the power in intensity oscillations with differ- ent components of the photospheric vector magnetic field using near simultaneous spectro-polarimetric observations of the sunspot from the Hinode spectropolarime- ter. The photospheric umbral power is strongly anti-correlated with the magnetic field strength and its line-of-sight component but there is a good correlation with the trans- verse component. A reversal of this trend is observed in the chromosphere except at low frequencies （V≤ 1.5 mHz）. The power in sunspot penumbrae is anti-correlated with the magnetic field parameters at all frequencies （1.0 ≤ v ≤ 8.0 mHz） in both the photosphere and chromosphere, except that the chromospheric power shows a strong correlation in the frequency range 3-3.5 mHz.

Analysis of sudden variations in photospheric magnetic fields during a large flare and their influences in the solar atmosphere

The solar active region NOAA 11719 produced a large two-ribbon flare on 2013 April 11. We have investigated sudden variations in the photospheric magnetic fields in this active region during the flare by employing magnetograms obtained in the spectral line Fe I 6173 A acquired by the Helioseismic and Magnetic Imager （HMI） onboard the Solar Dynamics Observatory （SDO） spacecraft. The analysis of the line-of-sight magnetograms from HMI show sudden and persistent magnetic field changes at different locations of the active region before the onset of the flare and during the flare. The vector magnetic field observations available from HMI also show coincident variations in the total magnetic field strength and its inclination angle at these locations. Using the simultaneous Dopplergrams obtained from HMI, we observe perturbations in the photospheric Doppler signals following the sudden changes in the magnetic fields in the aforementioned locations. The power spectrum analysis of these velocity signals shows enhanced acoustic power in these affected locations during the flare as compared to the pre-flare condition. Accompanying these observations, we have also used nearly simultaneous chromospheric observations obtained in the spectral line Ha 6562.8 A by the Global Oscillation Network Group （GONG） to study the evolution of flare- ribbons and intensity oscillations in this active region. The Ha intensity oscillations also show enhanced oscillatory power during the flare in the aforementioned locations. These results indicate that the transient Lorentz force associated with sudden changes in the magnetic fields could drive localized photospheric and chromospheric oscillations, like the flare-induced oscillations in the solar atmosphere.

Extracellular green synthesis of silver nanoparticles using Amazonian fruit Araza(Eugenia stipitata McVaugh)

An eco-friendly method for the extracellular synthesis of silver nanoparticles（AgNPs） using aqueous Araza fruit extract and their antioxidant activity was investigated. It was observed that UV–Vis absorption peak is dependent on various parameters such as pH, temperature, and change of time. The initial appearance of the yellow color with intense surface plasmon bands at 430-450 nm, then transmission electron microscopy, scanning electron microscopy and X-ray diffraction analysis revealed the formation of 15-45 nm sized, spherical and crystalline Ag NPs. Fourier transform infrared spectroscopy depicted that malic acid, citric acid, and carotenoids of Araza fruit involved in the synthesis of Ag NPs. In addition, the surface modified AgNPs（77.42%, 1mL） showed nearly double antioxidant efficiency than Araza fruit extract（35.30%, 1 mL） against 1, 1-diphenyl-2-picrylhydrazyl. The present study highlights the possibility of using the Araza fruit to synthesize AgNPs, which could be used effectively in the present and future antioxidant agent.

On the line profile changes observed during the X2.2 class flare in the active region NOAA 11158

The solar active region NOAA 11158 produced a series of flares during its passage through the solar disk. The first major flare （of class X2.2） of the current solar cycle occurred in this active region on 2011 February 15 around 01：50 UT. We have analyzed the Dopplergrams and magnetograms obtained by the Helioseismic and Magnetic Imager （HMI） instrument onboard Solar Dynamics Observatory to examine the photospheric velocity and magnetic field changes associated with this flare. The HMI instrument provides high-quality Doppler and magnetic maps of the solar disk with 0.5＂ spatial scale at a cadence of 45 s along with imaging spectroscopy. We have identified five locations of velocity transients in the active region during the flare. These transient velocity signals are located in and around the flare ribbons as observed by Hinode in the Ca II H wavelength and the footpoints of hard X-ray enhancement are in the energy range 12-25 keV from RHESSI. The changes in shape and width of two circular polarization states have been observed at the time of transients in three out of five locations. Forward modeling of the line profiles shows that the change in atmospheric parameters such as magnetic field strength, Doppler velocity and source function could explain the observed changes in the line profiles with respect to the pre-flare condition.

Mesiri:Mephisto Early Supernovae Ia Rapid Identifier

The early time observations of Type Ia supernovae(SNe Ia)play a crucial role in investigating and resolving longstanding questions about progenitor stars and the explosion mechanisms of these events.Colors of supernovae(SNe)in the initial days after the explosion can help differentiate between different types of SNe.However,the use of true color information to identify SNe Ia at the early-time explosion is still in its infancy.The Multi-channel Photometric Survey Telescope(Mephisto)is a photometric survey telescope equipped with three CCD cameras,capable of simultaneously imaging the same patch of sky in three bands(u,g,i or v,r,z),yielding real-time colors of astronomical objects.In this paper,we introduce a new time-series classification tool named Mephisto Early Supernovae Ia Rapid Identifier(Mesiri),which,for the first time,utilizes real-time color information to distinguish early-time SNe Ia from core-collapse supernovae.Mesiri is based on the deep learning approach and can achieve an accuracy of 96.75%±0.79%,and AUC of 98.87%±0.53%in case of single epoch random observation before the peak brightness.These values reach towards perfectness if additional data points on several night observations are considered.The classification with real-time color significantly outperforms that with pseudo-color,especially at the early time,i.e.,with only a few points of observations.The BiLSTM architecture shows the best performance compared to others that have been tested in this work.

Capuli cherry-mediated green synthesis of silver nanoparticles under white solar and blue LED light

In this article, the Capuli （Prunus serotina Ehrh. var. Capuli） cherry extract was used for the synthesis of silver nanoparticles （AgNPs） in the presence of white/visible solar and blue light-emitting diode （LED） light. For the characterization of the extract and the AgNPs, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy were employed, along with hydrodynamic particle size analysis, trans- mission electron microscopy and X-ray diffraction. The Ag nanospheres obtained using white light were 40-100 nm in diameter and exhibited an absorption peak at λmax= 445 nm, whereas those obtained using blue LED light were 20-80 nm in diameter with an absorption peak at λmax= 425 nm. Thermal analysis revealed that the content of biomolecules surrounding the AgNPs was about 55-65%, and it was also found that blue LED light AgNPs （56.28%, 0.05 mM） had a higher antioxidant efficacy than the white solar light AgNPs （33.42%, 0.05 mM） against l,l-diphenyl-2-picrylhydrazyl. The results indicate that obtaining AgNPs using a blue LED light may prove to be a simple, cost-effective and easily reproducible method for creating future nanopharmaceuticals.