Showing papers by "Shiv Nadar University published in 2012"

Furan containing diketopyrrolopyrrole copolymers: synthesis, characterization, organic field effect transistor performance and photovoltaic properties

Abstract: In this work, we report design, synthesis and characterization of solution processable low band gap polymer semiconductors, poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-phenylene} (PDPP-FPF), poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-naphthalene} (PDPP-FNF) and poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-anthracene} (PDPP-FAF) using the furan-containing 3,6-di(furan-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DBF) building block. As DBF acts as an acceptor moiety, a series of donor–acceptor (D–A) copolymers can be generated when it is attached alternatively with phenylene, naphthalene or anthracene donor comonomer blocks. Optical and electrochemical characterization of thin films of these polymers reveals band gaps in the range of 1.55–1.64 eV. These polymers exhibit excellent hole mobility when used as the active layer in organic thin-film transistor (OTFT) devices. Among the series, the highest hole mobility of 0.11 cm2 V−1 s−1 is achieved in bottom gate and top-contact OTFT devices using PDPP-FNF. When these polymers are used as a donor and [70]PCBM as the acceptor in organic photovoltaic (OPV) devices, power conversion efficiencies (PCE) of 2.5 and 2.6% are obtained for PDPP-FAF and PDPP-FNFpolymers, respectively. Such mobility values in OTFTs and performance in OPV make furan-containing DBF a very promising block for designing new polymer semiconductors for a wide range of organic electronic applications.

Fuzzy AHP for forest fire risk modeling

Abstract: Purpose – The purpose of study is linked to management and policy‐making strategies, such as forest management, land use planning and sustainable management of natural resources It aims to help prevent forest fire by taking precautions It also aims to be helpful for authorities coping during the event of occurrence of fireDesign/methodology/approach – The methodology paradigm applied here is based on knowledge‐based and analytic hierarchy process (AHP) techniques Knowledge‐based criteria involve topographic and different themes for risk assessment The assignment of value given to equation is significant due to its importanceFindings – Results are in strong agreement with actual fire occurrences in the past years The risk zones are identified according to past occurrence of fire The gradients of low‐ to high‐risk zones are according to fuel, topographic features and weather conditions Direction and aspect value were taken accordinglyOriginality/value – The paper presents forest fire risk zones de

Furan substituted diketopyrrolopyrrole and thienylenevinylene based low band gap copolymer for high mobility organic thin film transistors

Abstract: A novel solution processable donor–acceptor (D–A) based low band gap polymer semiconductor poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-thienylenevinylene} (PDPPF-TVT), was designed and synthesized by a Pd-catalyzed Stille coupling route An electron deficient furan based diketopyrrolopyrrole (DPP) block and electron rich thienylenevinylene (TVT) donor moiety were attached alternately in the polymer backbone The polymer exhibited good solubility, film forming ability and thermal stability The polymer exhibits wide absorption bands from 400 nm to 950 nm (UV-vis-NIR region) with absorption maximum centered at 782 nm in thin film The optical band gap (Eoptg) calculated from the polymer film absorption onset is around 137 eV The π-energy band level (ionization potential) calculated by photoelectron spectroscopy in air (PESA) for PDPPF-TVT is around 522 eV AFM and TEM analyses of the polymer reveal nodular terrace morphology with optimized crystallinity after 200 °C thermal annealing This polymer exhibits p-channel charge transport characteristics when used as the active semiconductor in organic thin-film transistor (OTFT) devices The highest hole mobility of 013 cm2 V−1 s−1 is achieved in bottom gate and top-contact OTFT devices with on/off ratios in the range of 106–107 This work reveals that the replacement of thiophene by furan in DPP copolymers exhibits such a high mobility, which makes DPP furan a promising block for making a wide range of promising polymer semiconductors for broad applications in organic electronics

Feature Combination in Kernel Space for Distance Based Image Hashing

Abstract: The paper presents a novel feature based indexing scheme for image collections. The scheme presents the extension of distance based hashing to kernel space for generating the indexing structure based on similarity in kernel space. The objective of the scheme is to incorporate multiple features for defining the image indexing space using the concept of multiple kernel learning. However, the indexing problems are defined with unique learning objective; therefore, a novel application of genetic algorithm is presented for the optimization task. The extensive evaluation of the proposed concept is performed for developing word based document indexing application of Devanagari, Bengali, and English scripts. In addition, the efficacy of the proposed concept is shown by experimental evaluations on handwritten digits and natural image collection.

Maintaining Approximate Maximum Weighted Matching in Fully Dynamic Graphs

Abstract: We present a fully dynamic algorithm for maintaining approximate maximum weight matching in general weighted graphs. The algorithm maintains a matching M whose weight is at least 1/8 M^{*} where M^{*} is the weight of the maximum weight matching. The algorithm achieves an expected amortized O(log n log C) time per edge insertion or deletion, where C is the ratio of the weights of the highest weight edge to the smallest weight edge in the given graph.

MQSPR modeling in materials informatics: a way to shorten design cycles?

Abstract: We demonstrate applications of quantitative structure–property relationship (QSPR) modeling to supplement first-principles computations in materials design. We have here focused on the design of polymers with specific electronic properties. We first show that common materials properties such as the glass transition temperature (T g) can be effectively modeled by QSPR to generate highly predictive models that relate polymer repeat unit structure to T g. Next, QSPR modeling is shown to supplement and guide first-principles density functional theory (DFT) computations in the design of polymers with specific dielectric properties, thereby leveraging the power of first-principles computations by providing high-throughput capability. Our approach consists of multiple rounds of validated MQSPR modeling and DFT computations to optimize the polymer skeleton as well as functional group substitutions thereof. Rigorous model validation protocols insure that the statistical models are able to make valid predictions on molecules outside the training set. Future work with inverse QSPRs has the potential to further reduce the time to optimize materials properties.

Nonclassical properties of states engineered by superpositions of quantum operations on classical states

Abstract: We consider an experimentally realizable scheme for manipulating quantum states using a general superposition of products of field annihilation () and creation () operators of the type (), with s2 + t2 = 1. Such an operation, when applied on states with classical features, is shown to introduce strong nonclassicality. We quantify the generated degree of nonclassicality by the negative volume of Wigner distribution in the phase space and investigate two other observable nonclassical features, sub-Poissonian statistics and squeezing. We find that the operation introduces negativity in the Wigner distribution of an input coherent state and changes the Gaussianity of an input thermal state. This provides the possibility of engineering quantum states with specific nonclassical features.

Reversible ferromagnetism in rutile TiO2 single crystals induced by nickel impurities

Abstract: We report a Ni impurity induced reversible ferromagnetism and surface conduction in rutile TiO2 crystals subjected to specific thermal annealing. For annealing in vacuum at 800 °C, a growing ferromagnetic signal is seen with time while for a similar annealing in air, the magnetism vanishes. The magnetism is concomitant with a surface conductivity which at low temperatures shows tunneling characteristics. Here, we show that Ni magnetic impurity (in TiO2 crystals at <100 ppm) under vacuum annealing segregates to the surface over a 50 nm layer where the Ni concentration exceeds 10%–20% and drops with subsequent air annealing.

Nonclassical properties of states engineered by superpositions of quantum operations on classical states

Abstract: We consider an experimentally realizable scheme for manipulating quantum states using a general superposition of products of field annihilation ($\hat{a}$) and creation ($\hat{a}^†$) operators of the type ($s \hat{a}\hat{a}^†+ t \hat{a}^†\hat{a}$), with $s^2 + t^2 = 1$. Such an operation, when applied on states with classical features, is shown to introduce strong nonclassicality. We quantify the generated degree of nonclassicality by the negative volume of Wigner distribution in the phase space and investigate two other observable nonclassical features, sub-Poissonian statistics and squeezing. We find that the operation introduces negativity in the Wigner distribution of an input coherent state and changes the Gaussianity of an input thermal state. This provides the possibility of engineering quantum states with specific nonclassical features.

A light emitting transistor based on a hybrid metal oxide-organic semiconductor lateral heterostructure

Abstract: A light-emitting field-effect transistor was fabricated, with its architecture based on a distinct heterojunction located midway between the source and drain contacts. Tetracene enabled hole transport on one side of the heterojunction (hole mobility ∼0.071 cm2/Vs), while amorphous solution-processed zinc tin oxide supported electron transport on the other side (electron mobility ∼0.81 cm2/Vs). The drain current vs. gate voltage curves of this device have a bell-shaped profile that is characteristic of lateral heterojunction bipolar field-effect transistors. The green light emission—from tetracene—closely follows the trend in drain current and is naked-eye visible in a darkened room.

Controllable quantum correlations of two-photon states generated using classically driven three-level atoms

Abstract: We investigate the dynamics of two-photon correlations generated by the interaction of a three-level atom in the $\Xi$, $\Lambda$ or V configuration, with two classical external driving fields, under the rotating-wave approximation, in the presence of level decays. Using the example of a rubidium atom in each configuration, with field strengths validating the single-photon approximation, we compute measurement based correlations, such as measurement induced disturbance (MID), quantum discord (QD), and quantum work deficit (WD), and compare the results with that of quantum entanglement (concurrence). Certain correlation properties observed are generic, model independent and consistent with known results, e.g., MID is an upper bound on QD, QD and WD are monotonic, and the generic correlation behavior is strongly affected by the purity of the photon states. We observe that the qualitative hierarchy, monotonicity and steady-state behavior of the correlations can be controlled by the choice of parameters such as atomic decay constants and external driving field strengths. We point out how particular configurations are better suited at generating monotonic correlations in specific regimes and how the steady-state correlation behavior and hierarchy are affected by the population dynamics of the density matrix for different parameters. The possibility of using well studied quantum optical systems such as the three-level atom to generate, characterize and parametrically control mixed state quantum correlations establishes an important step in the direction of their implementation in quantum information tasks.

Perfectly conducting tape-helix model for guided electromagnetic wave propagation

Abstract: The homogeneous boundary value problem arising in the propagation of electromagnetic waves guided by an open tape helix modelled to be of infinitesimal tape thickness and infinite tape-material conductivity is shown to be inherently ill posed. It is demonstrated how the ill posed problem may be regularised using the mollification method. The regularised boundary value problem is then solved to yield the approximate dispersion equation which takes the form of the solvability condition for an infinite system of linear homogeneous algebraic equations viz., the determinant of the infinite-order coefficient matrix is zero. For the numerical computation of the dispersion characteristic, all the entries of the symmetrically truncated version of the coefficient matrix are estimated by summing an adequate number of the rapidly converging (after regularisation) series for them. The tape-current distribution is estimated from the null-space vector of the truncated coefficient matrix corresponding to a specified root of the dispersion equation. A comparison of the numerical results with those for the anisotropically conducting model (that neglects the component of the tape-current density perpendicular to the winding direction) of the tape helix reveals that the propagation characteristic computed on the basis of the anisotropically conducting model could be substantially in error even for moderately wide tapes.

Development of large volume double ring penning plasma discharge source for efficient light emissions

Abstract: In this paper, the development of large volume double ring Penning plasma discharge source for efficient light emissions is reported. The developed Penning discharge source consists of two cylindrical end cathodes of stainless steel having radius 6 cm and a gap 5.5 cm between them, which are fitted in the top and bottom flanges of the vacuum chamber. Two stainless steel anode rings with thickness 0.4 cm and inner diameters 6.45 cm having separation 2 cm are kept at the discharge centre. Neodymium (Nd2Fe14B) permanent magnets are physically inserted behind the cathodes for producing nearly uniform magnetic field of ∼0.1 T at the center. Experiments and simulations have been performed for single and double anode ring configurations using helium gas discharge, which infer that double ring configuration gives better light emissions in the large volume Penning plasma discharge arrangement. The optical emission spectroscopy measurements are used to complement the observations. The spectral line-ratio technique ...

Furan containing diketopyrrolopyrrole copolymers : synthesis, characterization, organic field effect transistor performance and photovoltaic properties

Abstract: In this work, we report design, synthesis and characterization of solution processable low band gap polymer semiconductors, poly{3,6-difuran-2-yl-2,5-di(2- octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-phenylene} (PDPP-FPF), poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1, 4-dione-alt-naphthalene} (PDPP-FNF) and poly{3,6-difuran-2-yl-2,5-di(2- octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-anthracene} (PDPP-FAF) using the furan-containing 3,6-di(furan-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DBF) building block. As DBF acts as an acceptor moiety, a series of donor-acceptor (D-A) copolymers can be generated when it is attached alternatively with phenylene, naphthalene or anthracene donor comonomer blocks. Optical and electrochemical characterization of thin films of these polymers reveals band gaps in the range of 1.55-1.64 eV. These polymers exhibit excellent hole mobility when used as the active layer in organic thin-film transistor (OTFT) devices. Among the series, the highest hole mobility of 0.11 cm 2 V -1 s -1 is achieved in bottom gate and top-contact OTFT devices using PDPP-FNF. When these polymers are used as a donor and [70]PCBM as the acceptor in organic photovoltaic (OPV) devices, power conversion efficiencies (PCE) of 2.5 and 2.6% are obtained for PDPP-FAF and PDPP-FNF polymers, respectively. Such mobility values in OTFTs and performance in OPV make furan-containing DBF a very promising block for designing new polymer semiconductors for a wide range of organic electronic applications.

Experimental Investigation of Pseudospark generated electron beam

Abstract: The pseudospark (PS) discharge is, however, more recently recognized as a different type of discharge which is capable of generating electron beams with the highest combined current density and brightness of any known type of electron source. PS discharge is a specific type of gas discharge, which operates on the left-hand side of the hollow cathode analogy to the Paschen curve with axially symmetric parallel electrodes and central holes on the electrodes. The PS discharge generated electron beam has tremendous applications in plasma filled microwave sources where normal material cathode cannot be used. Analysis of the electron beam profile has been carried out experimentally for different applied voltages. The investigation has been done at different axial and radial location inside the drift tube in argon atmosphere. This paper represents experimentally derived axial and radial variation of the beam current inside the plasma filled drift tube of PS discharge based plasma cathode electron (PCE) gun. With the help of current density estimation the focusing and defocusing point of electron beam in axial direction can be analyzed. It has been further confirmed the successful propagation of electron beam in confined manner without any assistance of external magnetic field.

Graphs and networks in chemical and biological informatics: past, present and future.

Abstract: Chemical and biological network analysis has recently garnered intense interest from the perspective of drug design and discovery. While graph theoretic concepts have a long history in chemistry – predating quantum mechanics – and graphical measures of chemical structures date back to the 1970s, it is only recently with the advent of public repositories of information and availability of high-throughput assays and computational resources that network analysis of large-scale chemical networks, such as protein–protein interaction networks, has become possible. Drug design and discovery are undergoing a paradigm shift, from the notion of ‘one target, one drug’ to a much more nuanced view that relies on multiple sources of information: genomic, proteomic, metabolomic and so on. This holistic view of drug design is an incredibly daunting undertaking still very much in its infancy. Here, we focus on current developments in graph- and network-centric approaches in chemical and biological informatics, with partic...

Nonstoichiometric Mn-doped ZnO magic nanoclusters and their composite structures from ab initio calculations

Abstract: Undoped cages of (ZnO)${}_{n}$ nanoclusters are magic with $n$ $=$ 12 and 34. However with Mn doping, our ab initio calculations show that O rich, nonstoichiometric Zn${}_{12}$MnO${}_{15}$ and Zn${}_{34}$MnO${}_{37}$ nanoclusters obtained from $n$ $=$ 13 and 35, become magic with 1${\ensuremath{\mu}}_{B}$ magnetic moment. The Mn-doped nanoclusters can also be viewed as composite structures where a MnO${}_{x}$ species ($x$ $=$ 1--4) is attached to (ZnO)${}_{n}$ ($n$ $=$ 12 and 34) cages. Mn atoms can exist in a high oxidation state in these nanoclusters, with the highest binding energy for $x$ $=$ 3. Further replacement of Mn by Cr leads to a neutral, nonmagnetic Zn${}_{12}$CrO${}_{15}$ nanocluster with a large highest occupied molecular orbital and lowest unoccupied molecular orbital gap of 2.24 eV. These results provide new ground to understand doped nanostructures of ZnO and may also shed light on magnetism in Mn-doped ZnO thin films.

Of Poverty and Plastic: Scavenging and Scrap Trading Entrepreneurs in India's Urban Informal Economy

Abstract: This volume applies the interdisciplinary 'field economics' approach to poverty analysis. The work is based on extensive fieldwork in the pre-urban edge of the sprawling metropolis of Delhi It assesses the economic, social, and political institutions and processes that structure the well-being, agency, and activities of the poor who are waste scavengers and involved with plastic recycling. Using a mix of survey and ethnographic data, it tells the complete story of how the waste picker at the lowest level of the chain fares in comparison to other kinds of occupational groups engaged in different parts of the scavenging and recycling chain, as well as in other parts of the informal economy. It focuses on the following themes: how occupational choices are dictated by low caste status; how these groups negotiate and surmount market failures and state failures to create a viable informal economy supporting numerous livelihoods and businesses; and how these groups gain or lose from patronage links at the level of the state government and national political parties.

Tracking electron-induced carbon contamination and cleaning of Ru surfaces by Auger electron spectroscopy

Abstract: Extreme ultraviolet (EUV) radiation induced growth of carbon and oxygen desorption were investigated on a Ru surface by Auger electron spectroscopy (AES) in the presence and absence of additional photoelectrons (PEs) from a focusing Ru mirror. A decrease in EUV reflectivity with carbon growth in the presence of additional PEs has been observed. Conversely, a carbonaceous Ru surface was cleaned in sequential AES, and discussed in terms of secondary electron assisted dissociation of residual hydrocarbons and water molecules, followed by a chemical reaction between adsorbed carbon and oxygen atoms.

SVM prediction of ligand-binding sites in bacterial lipoproteins employing shape and physio-chemical descriptors

Abstract: Bacterial lipoproteins play critical roles in various physiological processes including the maintenance of pathogenicity and numbers of them are being considered as potential candidates for generating novel vaccines. In this work, we put forth an algorithm to identify and predict ligand-binding sites in bacterial lipoproteins. The method uses three types of pocket descriptors, namely fpocket descriptors, 3D Zernike descriptors and shell descriptors, and combines them with Support Vector Machine (SVM) method for the classification. The three types of descriptors represent shape-based properties of the pocket as well as its local physio-chemical features. All three types of descriptors, along with their hybrid combinations are evaluated with SVM and to improve classification performance, WEKA-InfoGain feature selection is applied. Results obtained in the study show that the classifier successfully differentiates between ligand-binding and non-binding pockets. For the combination of three types of descriptors, 10 fold cross-validation accuracy of 86.83% is obtained for training while the selected model achieved test Matthews Correlation Coefficient (MCC) of 0.534. Individually or in combination with new and existing methods, our model can be a very useful tool for the prediction of potential ligand-binding sites in bacterial lipoproteins.

Social Entrepreneurship: A Strategic Perspective

Abstract: Social entrepreneurship is fast emerging as an innovative approach to deal with the complex social needs of development, especially operating under the neoliberal paradigm of governance. Given its compelling language of hope and compassion, the phenomenon has drawn attention of both practitioners and academicians alike. Inspite of the widespread interest, consensus about its forms and definition has remained elusive and much confusion exists about it being an extension of voluntarism or a new form of entrepreneurship. By doing a cross-case analysis of four select social enterprises, this paper draws inferences about their operational aspects and concludes that it needs to be viewed as a new strategic process of combining both the welfare spirit of voluntarism and the business mindsets of entrepreneurship.

Automated processing and uninterrupted supply of hydrogen: A road map of future green energy

Abstract: A comprehensive hydrogen processing unit (HPU) is presented for uninterrupted supplying of it at desired pressure rate. The pressurized Hydrogen is used for the cooling of large size generators in integrated gasification combined cycle power plants. It can also be seen as one of the future sources of fuel for automobile applications. Thereby, it reduces the chances of green house gases emission. Equally, Hydrogen can be utilized as a future source of energy for the automobiles. A novel HPU clubbed with highly reliable and efficient process automation system is proposed. The work includes a comparison between the proposed and the existing systems in terms of system reliability. The algorithm for system reliability is developed on MATLAB platform. The effectiveness of real-time featured proposed HPU is validated by computer simulation. The entire process automation system is designed and simulated on FT-View32 Works. It meets the specifications guided by IEEE C37.1-2007, IEC 61131-3 and IEEE 1413-2010.

Introduction of Probability Concepts in Physics—The Path to Statistical Mechanics

Abstract: It was an Italian gambler who gave us the first scientific study of probability theory. But Girolamo Cardano, also known as Hieronymus Cardanus or Jerome Cardan (1501–1576), was no ordinary gambler. He was also an accomplished mathematician, a reputed physician, and author. Born in Pavia, Italy, Cardan was the illegitimate son of Fazio Cardano, a Milan lawyer and mathematician, and Chiara Micheria. In addition to his law practice, Fazio lectured on geometry at the University of Pavia and at the Piatti Foundation and was consulted by the likes of Leonardo da Vinci on matters of geometry. Fazio taught his son mathematics and Girolamo started out as his father’s legal assistant, but then went on to study medicine at Pavia University, earning his doctorate in medicine in 1525. But on account of his confrontational personality, he had a difficult time finding work after completing his studies. In 1525, he applied to the College of Physicians in Milan, but was not admitted owing to his illegitimate birth. Upon his father’s death, Cardan squandered his bequest and turned to gambling, using his understanding of probability to make a living off card games, dice, and chess. Cardan’s book on games of chance, Liber de ludo aleae (On Casting the Die, written in the 1560s, but not published until 1663), contains the first ever exploration of the laws of probability, as well as a section on effective cheating methods! In this book, he considered the fundamental scientific principles