Kodaikanal Digitized White-light Data Archive (1921-2011): Analysis of various solar cycle features

Long-term sunspot observations are key to understand and predict the solar activities and its effects on the space weather.Consistent observations which are crucial for long-term variations studies,are generally not available due to upgradation/modifications of observatories over the course of time. We present the data for a period of 90 years acquired from persistent observation at the Kodaikanal observatory in India. We use an advanced semi-automated algorithm to detect the sunspots form each calibrated white-light image. Area, longitude and latitude of each of the detected sunspots are derived. Implementation of a semi-automated method is very necessary in such studies as it minimizes the human bias in the detection procedure. Daily, monthly and yearly sunspot area variations obtained from the Kodaikanal, compared well with the Greenwich sunspot area data. We find an exponentially decaying distribution for the individual sunspot area for each of the solar cycles. Analyzing the histograms of the latitudinal distribution of the detected sunspots, we find Gaussian distributions, in both the hemispheres, with the centers at $\sim$15$^{\circ}$ latitude. The height of the Gaussian distributions are different for the two hemispheres for a particular cycle. Using our data, we show clear presence of Waldmeier effect which correlates the rise time with the cycle amplitude. Using the wavelet analysis, we explored different periodicities of different time scales present in the sunspot area times series.Comment: Accepted for Publication in A&

Resonant enhancement of ultracold photoassociation rate by electric field induced anisotropic interaction

We study the effects of a static electric field on the photoassociation of a heteronuclear atom-pair into a polar molecule. The interaction of permanent dipole moment with a static electric field largely affects the ground state continuum wave function of the atom-pair at short separations where photoassociation transitions occur according to Franck-Condon principle. Electric field induced anisotropic interaction between two heteronuclear ground state atoms leads to scattering resonances at some specific electric fields. Near such resonances the amplitude of scattering wave function at short separation increases by several orders of magnitude. As a result, photoaasociation rate is enhanced by several orders of magnitude near the resonances. We discuss in detail electric field modified atom-atom scattering properties and resonances. We calculate photoassociation rate that shows giant enhancement due to electric field tunable anisotropic resonances. We present selected results among which particularly important are the excitations of higher rotational levels in ultracold photoassociation due to electric field tunable resonances.Comment: 14 pages,9 figure

The Prospective Role of Plant Products in Radiotherapy of Cancer: A Current Overview

Treatment of cancer often requires exposure to radiation, which has several limitations involving non-specific toxicity toward normal cells, reducing the efficacy of treatment. Efforts are going on to find chemical compounds which would effectively offer protection to the normal tissues after radiation exposure during radiotherapy of cancer. In this regard, plant-derived compounds might serve as “leads” to design ideal radioprotectors/radiosensitizers. This article reviews some of the recent findings on prospective medicinal plants, phytochemicals, and their analogs, based on both in vitro and in vivo tumor models especially focused with relevance to cancer radiotherapy. Also, pertinent discussion has been presented on the molecular mechanism of apoptotic death in relation to the oxidative stress in cancer cells induced by some of these plant samples and their active constituents

Synthesis of benzothiazolopyrazoloisonicotinohydrazide derivatives and their nitro regioisomers for antitubercular activity

The history of incessant struggle and the current global burden associated with emerging infectious disease especially tuberculosis, guided us to define the scope of this research project, and to identify research gaps in synthesizing some heterocyclic compounds for anti-tubercular activity. In this research project, we have synthesized a series of novel heterocyclic (benzothiazoles) compounds viz N'-((1-(7-chloro-6-fluorobenzo[d]thiazol-2-yl)-3-phenyl-1H-pyrazol-4-yl) methylene)isonicotinohydrazide 12a-c their 5-nitro 15a-c and 4-nitro 18a-c derivatives, by a series of reactions of their respective synthons. The completion of reaction and the purity of the synthesized compounds have been established by chromatographic analysis. All the newly synthesized compounds satisfactorily show acceptable analysis for their anticipated structures, which have been confirmed based on physicochemical and spectral data. These newly synthesized compounds have been primarily evaluated for their in vitro anti-tubercular activity by Ziehl-Neelsen stain method. Compounds 15a, 15b, 15c, 18b and 18c have shown 100% inhibition at 25 mg/ mL and MIC values of around 45 nM against M. tuberculosis H37Rv (ATCC 27294). Cytotoxicity on THP-1 cell line shows that all the tested compounds are safe.

Synthesis of benzothiazolopyrazoloisonicotinohydrazide derivatives and their nitro regioisomers for antitubercular activity

1388-1399The history of incessant struggle and the current global burden associated with emerging infectious disease especially tuberculosis, guided us to define the scope of this research project, and to identify research gaps in synthesizing some heterocyclic compounds for anti-tubercular activity. In this research project, we have synthesized a series of novel heterocyclic (benzothiazoles) compounds viz N'-((1-(7-chloro-6-fluorobenzo[d]thiazol-2-yl)-3-phenyl-1H-pyrazol-4-yl) methylene)isonicotinohydrazide 12a-c their 5-nitro 15a-c and 4-nitro 18a-c derivatives, by a series of reactions of their respective synthons. The completion of reaction and the purity of the synthesized compounds have been established by chromatographic analysis. All the newly synthesized compounds satisfactorily show acceptable analysis for their anticipated structures, which have been confirmed based on physicochemical and spectral data. These newly synthesized compounds have been primarily evaluated for their in vitro anti-tubercular activity by Ziehl-Neelsen stain method. Compounds 15a, 15b, 15c, 18b and 18c have shown 100% inhibition at 25 mg/ mL and MIC values of around 45 nM against M. tuberculosis H37Rv (ATCC 27294). Cytotoxicity on THP-1 cell line shows that all the tested compounds are safe

Revealing the mechanical and microstructural performance of multiphase steels during tensile, forming and flanging operations

The mechanical performance of Dual Phase (DP) and Complex Phase (CP) steels was investigated by SEM analysis, tensile testing, Forming Limit Curve investigation and flange formability testing. The alloys of interest were Dual Phase (DP) untempered, Dual Phase (DP) tempered and Complex Phase (CP) steels. Phase content analysis showed that the distribution of the ferrite and martensite phases was the same for the two DP alloys, but the grain size and condition (tempered/untempered) for the martensite islands was much different in the two alloys. In the tempered DP steel, the smaller grain size for the martensite and the tempering process resulted in increased elongation, more formability and ability to form a flange (flangeability). In CP steels the soft ferrite phase is replaced by harder bainite, yielding a bainitic-martensitic microstructure. Bainite reduced the total elongation of the alloy during tensile testing, reduced the formability (especially under plane strain conditions) of the alloy but improved the flangeability of the alloy. Under flanging conditions, CP steels deformed to higher strains, at tighter radii with minimum springback. Microstructural inspections at the outer radius of the flanged specimens revealed that in CP steels bainite deforms similarly to martensite, therefore the strain partitioning is smaller in CP steels in comparison to DP steels. Plastic deformation in CP steels upon flanging occurs with the formation of strong slip bands in both martensite and bainite. In contrast, the martensite and ferrite grains in DP steels deform quite differently leading to strong strain localisations. Void nucleation and cracking occurred at the martensite islands or within the soft ferrite phase next to the martensite islands. In CP steels no voids or damage was observed within the matrix. A special case study was done with a thicker and stronger alloy, a Martensitic 1400 steel to reveal the flangeability limits for advanced high strength steels. Neither cracks nor damage were observed visually on the flanged specimens. However SEM observations at the outer radius of the flanged samples revealed significant void growth at inclusion sites and cracks nucleating within the matrix adjacent to the inclusions.Publisher Statement: This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/)</p

Three-dimensional racetrack memory devices designed from freestanding magnetic heterostructures

The fabrication of three-dimensional nanostructures is key to the development of next-generation nanoelectronic devices with a low device footprint. Magnetic racetrack memory encodes data in a series of magnetic domain walls that are moved by current pulses along magnetic nanowires. To date, most studies have focused on two-dimensional racetracks. Here we introduce a lift-off and transfer method to fabricate three-dimensional racetracks from freestanding magnetic heterostructures grown on a water-soluble sacrificial release layer. First, we create two-dimensional racetracks from freestanding films transferred onto sapphire substrates and show that they have nearly identical characteristics compared with the films before transfer. Second, we design three-dimensional racetracks by covering protrusions patterned on a sapphire wafer with freestanding magnetic heterostructures. We demonstrate current-induced domain-wall motion for synthetic antiferromagnetic three-dimensional racetracks with protrusions of up to 900 nm in height. Freestanding magnetic layers, as demonstrated here, may enable future spintronic devices with high packing density and low energy consumption