<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

(SoNS) School of Natural Sciences

High altitude (HA), defined as approximately 3000–5000 m, considerably alters physiological and psychological parameters within a few hours. Chronic HA-mediated hypoxia (5000 m) results in permanent neuronal damage to the human brain that persists for one year or longer, even after returning to sea level. At HA, there is a decrease in barometric pressure and a consequential reduction in the partial pressure of oxygen (PO2), an extreme environmental condition to which humans are occasionally exposed. This condition is referred to as hypobaric hypoxia (HBH), which represents the most unfavourable characteristics of HA. HBH causes the disruption of oxygen availability to tissue. However, no review article has explored the impact of HBH on cognitive functions or the potential therapeutic agents for HBH. Therefore, the present review aimed to describe the impact of HBH on both physiological and cognitive functions, specifically learning and memory. Finally, the potential therapeutic agents for the treatment of HBH-induced cognitive impairment are discussed. © Penerbit Universiti Sains Malaysia, 2014.

World University root node

Life Sciences

Malaysian Journal of Medical Sciences

Effect of hypobaric hypoxia on cognitive functions and potential therapeutic agents

We report the electronic structures of Ta-doped anatase TiO2 thin films grown by pulsed laser deposition (PLD) with varying magnetization using a combination of first-principles calculations and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The roles of Ta doping and Ti vacancies are clarified, and the observed room-temperature ferromagnetism is attributed to the localized magnetic moments at Ti vacancy sites ferromagnetically ordered by electron charge carriers. O K-edge spectra exhibit significant polarization dependence which is discussed and supported by first-principles calculations in relation to both the crystal symmetry and the formation of defects. In particular, anomalous spectral-weight transfer across the entire O K edge for the ferromagnetic thin film is associated exclusively with the occurrence of Ti vacancies and strong correlation effects, which result in the enhancement of the direct interaction between oxygen sites and of the anisotropy of the eg-pσ hybridizations in the out-of-plane component. Our results show that O K-edge NEXAFS spectra can provide reliable experimental probes capable of revealing cationic defects that are intimately related to the ferromagnetism in transition metal oxides. © 2013 American Physical Society.

Physics

Fulltext

Physical Review B - Condensed Matter and Materials Physics

Cationic vacancies and anomalous spectral-weight transfer in Ti 1-xTaxO2 thin films studied via polarization-dependent near-edge x-ray absorption fine structure spectroscopy

The relationship between charge carrier lifetime and mobility in a bulk heterojunction based organic solar cell, utilizing diketopyrrolopyrole- naphthalene co-polymer and PC71BM in the photoactive blend layer, is investigated using the photoinduced charge extraction by linearly increasing voltage technique. Light intensity, delay time, and temperature dependent experiments are used to quantify the charge carrier mobility and density as well as the temperature dependence of both. From the saturation of photoinduced current at high laser intensities, it is shown that Langevin-type bimolecular recombination is present in the studied system. The charge carrier lifetime, especially in Langevin systems, is discussed to be an ambiguous and unreliable parameter to determine the performance of organic solar cells, because of the dependence of charge carrier lifetime on charge carrier density, mobility, and type of recombination. It is revealed that the relation between charge mobility (μ) and lifetime (τ) is inversely proportional, where the μτ product is independent of temperature. The results indicate that in photovoltaic systems with Langevin type bimolecular recombination, the strategies to increase the charge lifetime might not be beneficial because of an accompanying reduction in charge carrier mobility. Instead, the focus on non-Langevin mechanisms of recombination is crucial, because this allows an increase in the charge extraction rate by improving the carrier lifetime, density, and mobility simultaneously. © 2013 AIP Publishing LLC.

Journal of Applied Physics

Relation between charge carrier mobility and lifetime in organic photovoltaics

The interrelationship between pathogen infection and host mobility is of great importance for successful spread of disease in spatial pest population. As spread of infection depends on horizontal transmission of pathogen, there are numerous factors like susceptibility, latent period, host movement that influence overall effectiveness of the control policy. Initiation of new infection cycle depends on density of infected inoculum in the site. So, spatial movement of infected hosts during the course of infection influence the dynamics. Also, infected individuals are more vulnerable to predators and hence production of virus particles in the site depends on predation to some extent. We derive a four dimensional delayed reaction-diffusion model in one spatial dimension and compute the minimum travelling speed of transmission of infection. We show that the minimum speed is sensitive to several parameters of the system. For example, the minimum speed decreases only with increase in delay in lysis process, but otherwise it increases with increase in force of infection, diffusivity of infectives or per capita virus production. A concluding discussion with numerical simulation is presented in the end. © 2013.

Mathematics

Mathematical Biosciences

Spatiotemporal dynamics of insect pest population under viral infection

Let K be a finite extension of a characteristic zero field F. We say that a pair of n × n matrices (A,B) over F represents K if K ≅ F[A]/〈B〉, where F[A] denotes the subalgebra of Mn(F) containing A and 〈B〉 is an ideal in F[A], generated by B. In particular, A is said to represent the field K if there exists an irreducible polynomial q(x) ∈ F[x] which divides the minimal polynomial of A and K ≅ F[A]/〈q(A)〉. In this paper, we identify the smallest order circulant matrix representation for any subfield of a cyclotomic field. Furthermore, if p is a prime and K is a subfield of the p-th cyclotomic field, then we obtain a zero-one circulant matrix A of size p × p such that (A, J) represents K, where J is the matrix with all entries 1. In case, the integer n has at most two distinct prime factors, we find the smallest order 0, 1-companion matrix that represents the n-th cyclotomic field. We also find bounds on the size of such companion matrices when n has more than two prime factors. © 2013 The Indian National Science Academy.

Indian Journal of Pure and Applied Mathematics

Representation of cyclotomic fields and their subfields

Scattering is an important phenomenon which is observed in systems ranging from the micro- to macroscale. In the context of nuclear reaction theory, the Heidelberg approach was proposed and later demonstrated to be applicable to many chaotic scattering systems. To model the universal properties, stochasticity is introduced to the scattering matrix on the level of the Hamiltonian by using random matrices. A long-standing problem was the computation of the distribution of the off-diagonal scattering-matrix elements. We report here an exact solution to this problem and present analytical results for systems with preserved and with violated time-reversal invariance. Our derivation is based on a new variant of the supersymmetry method. We also validate our results with scattering data obtained from experiments with microwave billiards. © 2013 American Physical Society.

Physical Review Letters

Distribution of scattering matrix elements in quantum chaotic scattering

The capillary flow in SU8 based microfluidic devices fabricated in SF-100 by lithographic technique has been recorded and analysed in this report. Leakage free microfluidic flow is achieved by indirect bonding between polymethyl methacrylate (PMMA) coated glass lid surface and SU8 channel substrate during hard baking. The working liquids are dyed ethylene glycol, dyed ethanol, dyed isopropyl alcohol (IPA) and dyed liquid mixture (water and IPA). The capillary flow of dyed ethylene glycol is found to be slower in each device due to higher viscosity and lower surface wettability as compared to other working liquids. Square SU8 micropillar arrays (80 μm and 120 μm of side lengths) are fabricated on the glass bottom wall surface of SU8 based microchannel. The capillary flow of any particular working liquid is observed to be faster through the square micropillars of smaller side length due to their lower surface area to volume ratio in the device. Also, the capillary flow of polar liquids is found to be faster on the microchannel surface of higher polar component of surface free energy. The above results are highly significant to control the speed of capillary flow in lab-on-a-chip systems. © 2012 Elsevier Ltd.

International Journal of Adhesion and Adhesives

Effects of liquid viscosity, surface wettability and channel geometry on capillary flow in SU8 based microfluidic devices

Catalytic signal amplification was used for the colorimetric detection of CN− in aqueous media by using the enzyme catalase in tandem with mesoporous silica nanoparticle based synthetic HRP enzyme mimic Fe-MSNs. Signal amplification up to a maximum of eight fold was observed for the reporter “oxidized TMB” with respect to the added CN− ion. © 2013 The Royal Society of Chemistry.

Chemistry

Chemical Communications

Catalytic signal amplification using [FeIII(biuret-amide)]-mesoporous silica nanoparticles: Visual cyanide detection

31P nuclear-magnetic-resonance (NMR) study in the trimer spin chain compound Ca3Cu2Ni(PO4)4 is performed in the presence of different external magnetic fields in the temperature range 4-300 K. The results suggest that the three magnon mediated scattering process which was the dominant contribution to 1/T1 in the pure compound Ca3Cu3(PO4)4, has negligible contribution in Ca3Cu2Ni(PO4) 4, with the two magnon mediated Raman process being dominant. The linear variation of nuclear spin lattice relaxation rate 1/T1T with the magnetic susceptibility $\chi$ indicates that the Q component of magnetic susceptibility $\chi$(Q) is nearly proportional to $\chi$, where Q is the antiferromagnetic wave vector. A change in the slope of 1/T1T with respect to $\chi$ near 15 K suggests a change in the antiferromagnetic spin fluctuation spectrum. Below 15 K, the spin diffusion mechanism governs the 1/T1 process. This could be a signature of the development of short range magnetic correlation or due to the contribution arising from the paramagnetic impurity spins. {\textcopyright} 2013 Elsevier B.V. All rights reserved.

Physica B: Condensed Matter

Low energy spin dynamics in trimer spin chain compound Ca 3Cu2Ni(PO4)4: 31P NMR study

We investigate the blend morphology and performance of bulk heterojunction organic photovoltaic devices comprising the donor polymer, pDPP-TNT (poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1, 4-dione-alt-naphthalene}) and the fullerene acceptor, [70]PCBM ([6,6]-phenyl C71-butyric acid methyl ester). The blend morphology is heavily dependent upon the solvent system used in the fabrication of thin films. Thin films spin-coated from chloroform possess a cobblestone-like morphology, consisting of thick, round-shaped [70]PCBM-rich mounds separated by thin polymer-rich valleys. The size of the [70]PCBM domains is found to depend on the overall film thickness. Thin films spin-coated from a chloroform:dichlorobenzene mixed solvent system are smooth and consist of a network of pDPP-TNT nanofibers embedded in a [70]PCBM-rich matrix. Rinsing the films in hexane selectively removes [70]PCBM and allows for analysis of domain size and purity. It also provides a means for investigating exciton dissociation efficiency through relative photoluminescence yield measurements. Devices fabricated from chloroform solutions show much poorer performance than the devices fabricated from the mixed solvent system; this disparity in performance is seen to be more pronounced with increasing film thickness. The primary cause for the improved performance of devices fabricated from mixed solvents is attributed to the greater donor-acceptor interfacial area and resulting greater capacity for charge carrier generation. © The Royal Society of Chemistry 2013.