A study of photoionized gas in two HII regions of the N44 complex in the LMC using MUSE observations

We use the optical integral field observations with Multi-Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope, together with CLOUDY photoionization models to study ionization structure and physical conditions of two luminous HII regions in N44 star-forming complex of the Large Magellanic Cloud. The spectral maps of various emission lines reveal a stratified ionization geometry in N44 D1. The spatial distribution of [O I] 6300A emission in N44 D1 indicates a partially covered ionization front at the outer boundary of the H II region. These observations reveal that N44 D1 is a Blister HII region. The [O I] 6300A emission in N44 C does not provide a well-defined ionization front at the boundary, while patches of [S II] 6717 A and [O I] 6300A emission bars are found in the interior. The results of spatially resolved MUSE spectra are tested with the photoionization models for the first time in these HII regions. A spherically symmetric ionization-bounded model with a partial covering factor, which is appropriate for a Blister HII region can well reproduce the observed geometry and most of the diagnostic line ratios in N44 D1. Similarly, in N44 C we apply a low density and optically thin model based on the observational signatures. Our modeling results show that the ionization structure and physical conditions of N44 D1 are mainly determined by the radiation from an O5 V star. However, local X-rays, possibly from supernovae or stellar wind, play a key role. In N44 C, the main contribution is from three ionizing stars.Comment: Accepted for publication in Ap

Pancreatic Cancer and Therapy: Role and Regulation of Cancer Stem Cells

Despite significant improvements in clinical management, pancreatic cancer (PC) remains one of the deadliest cancer types, as it is prone to late detection with extreme metastatic properties. The recent findings that pancreatic cancer stem cells (PaCSCs) contribute to the tumorigenesis, progression, and chemoresistance have offered significant insight into the cancer malignancy and development of precise therapies. However, the heterogeneity of cancer and signaling pathways that regulate PC have posed limitations in the effective targeting of the PaCSCs. In this regard, the role for K-RAS, TP53, Transforming Growth Factor-β, hedgehog, Wnt and Notch and other signaling pathways in PC progression is well documented. In this review, we discuss the role of PaCSCs, the underlying molecular and signaling pathways that help promote pancreatic cancer development and metastasis with a specific focus on the regulation of PaCSCs. We also discuss the therapeutic approaches that target different PaCSCs, intricate mechanisms, and therapeutic opportunities to eliminate heterogeneous PaCSCs populations in pancreatic cancer

Shape- and Interface-Induced Control of Spin Dynamics of Two-Dimensional Bicomponent Magnonic Crystals

Controlled fabrication of periodically arranged embedded nanostructures with strong interelement interaction through the interface between the two different materials has great potential applications in spintronics, spin logic, and other spin-based communication devices. Here, we report the fabrication of two-dimensional bicomponent magnonic crystals in form of embedded Ni₈₀Fe₂₀ nanostructures in Co₅₀Fe₅₀ thin films by nanolithography. The spin wave (SW) spectra studied by a broadband ferromagnetic resonance spectroscopy showed a significant variation as the shape of the embedded nanostructure changes from circular to square. Significantly, in both shapes, a minimum in frequency is obtained at a negative value of bias field during the field hysteresis confirming the presence of a strong exchange coupling at the interface between the two materials, which can potentially increase the spin wave propagation velocity in such structures leading to faster gigahertz frequency magnetic communication and logic devices. The spin wave frequencies and bandgaps show bias field tunability, which is important for above device applications. Numerical simulations qualitatively reproduced the experimental results, and simulated mode profiles revealed the spatial distribution of the SW modes and internal magnetic fields responsible for this observation. Development of such controlled arrays of embedded nanostructures with improved interface can be easily applied to other forms of artificial crystals

Grape extract assisted green synthesis of reduced graphene oxide for water treatment application

Grapes (Vitis vinifera) extract was explored as a “green reducing agent” for the preparation of reduced graphene oxide (RGO) from graphene oxide (GO). The effect of reduction time on physical, chemical and optical properties of the RGO was also investigated. Synthesized RGO samples exhibited excellent activity as an adsorbent for the removal of organic dye. Proposed synthesis is environmental friendly, cost effective and promising for the large scale production of RGO

Two new species of Pleciobates (Hemiptera: Gerromorpha: Gerridae) from India, with a key to the species of Pleciobates

Jehamalar, E. Eyarin, Chandra, Kailash, Zettel, Herbert, Basu, Srimoyee, Barman, Bijita, Gupta, Susmita, Subramanian, K. A. (2014): Two new species of Pleciobates (Hemiptera: Gerromorpha: Gerridae) from India, with a key to the species of Pleciobates. Zootaxa 3866 (3): 435-445, DOI: 10.11646/zootaxa.3866.3.

Tunable Magnetization Dynamics in Interfacially Modified Ni81Fe19/Pt Bilayer Thin Film Microstructures

Interface modification for control of ultrafast magnetic properties using low-dose focused ion beam irradiation is demonstrated for bilayers of two technologically important materials: Ni81Fe19 and Pt. Magnetization dynamics were studied using an all-optical time-resolved magneto-optical Kerr microscopy method. Magnetization relaxation, precession, damping and the spatial coherence of magnetization dynamics were studied. Magnetization precession was fitted with a single-mode damped sinusoid to extract the Gilbert damping parameter. A systematic study of the damping parameter and frequency as a function of irradiation dose varying from 0 to 3.3 pC/μm2 shows a complex dependence upon ion beam dose. This is interpreted in terms of both intrinsic effects and extrinsic two-magnon scattering effects resulting from the expansion of the interfacial region and the creation of a compositionally graded alloy. The results suggest a new direction for the control of precessional magnetization dynamics, and open the opportunity to optimize high-speed magnetic devices

Electrophoretic deposition of plasmonic nanocomposite for the fabrication of dye-sensitized solar cells

73-80TiO2-Ag nanocomposites have been prepared by hydrothermal process for the preparation of photoelectrode for dye-sensitized solar cells. The formation of TiO2-Ag nanocomposites have been confirmed by the transmission electron microscopy (TEM), UV-Vis spectroscopy, X-ray diffraction and energy dispersive X-ray analysis. The TEM images confirm that silver nanoparticles of average size 30 nm are dispersed inside the TiO2 matrix. Electrophoretic deposition technique (EPD) is successfully utilized to incorporate TiO2-Ag nanocomposites in commercially available TiO2 nanoparticle to prepare photoelectrode on transparent oxide substrate. Incorporation of TiO2-Ag nanocomposites by EPD technique has been done in different ways: in all the layers of TiO2 photoelectrode and in only the top layer of TiO2 photoelectrode. X-ray diffraction, field effect scanning electron microscopy in back scattered mode and photoluminescence (PL) spectroscopy study confirm the presence of TiO2-Ag nanostructure in prepared photoelectrode. The current-voltage characteristic shows 78% and 67% enhancement of photocurrent and power conversion efficiency (PCE) respectively in the DSSC with Ag incorporated photoelectrode compared to the cell without Ag nanoparticles and maximum PCE obtained in DSSC with TiO2-Ag is 7.5%