Showing papers by "Shiv Nadar University published in 2017"

Sulfur Copolymer: A New Cathode Structure for Room-Temperature Sodium–Sulfur Batteries

Abstract: High-energy electrochemical storage containing earth abundant materials could be a choice for future battery development. Recent research reports indicated the possibility of room-temperature sodium-ion–sulfur chemistry for large storage including smart grids. Here, we report a room-temperature sodium–sulfur battery cathode that will address the native downsides of a sodium–sulfur battery, such as polysulfide shuttling and low electrical conductivity of elemental sulfur. In this Letter, we use a sustainable route which ensures a large sulfur confinement (i.e., ∼90 wt %) in the cathode structure. The sulfur-embedded polymer is realized via thermal ring-opening polymerization of benzoxazine in the presence of elemental sulfur (CS90) and later composite with reduced graphene oxide (rGO). The resulting CS90 allows a homogeneous distribution of sulfur due to in situ formation of the polymer backbone and allows maximum utilization of sulfur. This unique electrode structure bestows CS90–rGO with an excellent Cou...

Aloe vera assisted facile green synthesis of reduced graphene oxide for electrochemical and dye removal applications

Abstract: In the present work, the suitability of Aloe vera (AV) as a ‘green reducing agent’ has been investigated for the reduction of graphene oxide (GO). The extent of reduction was studied by varying the amount of AV. The physical and chemical properties of the GO and reduced graphene oxide (rGO) were investigated using UV-Vis spectrophotometry, FT-IR spectroscopy, High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Electron Diffraction (SAED). Partially reduced graphene oxide sheets obtained with 7.5 g of AV (rGO-7.5) demonstrated a maximum reduction efficiency of about 73% as evident from FT-IR data. Cyclic voltammetry and electrochemical impedance spectroscopy studies revealed a significant enhancement in current density and a decrease in charge transfer resistance for the rGO-7.5 sample. Moreover, the as prepared rGO-7.5 sample showed a remarkable dye removal ability with a maximum efficiency of ∼98%. The enhanced surface area, π–π interaction and strong electrostatic attraction were correlated with the dye removal capability. The adsorption kinetics were also studied and pseudo second order adsorption phenomena were confirmed. The recyclability of the rGO-7.5 sample was further investigated and an excellent desorption capability was established.

Advances on transition metal oxides catalysts for formaldehyde oxidation: A review

Abstract: This article highlights recent advances in the development of transition metal-based catalysts for formaldehyde oxidation, particularly the enhancement of their catalytic activity for low-temperature oxidation. Various factors that enhance low-temperature activity are reviewed, such as morphology and tunnel structures, synthesis methods, specific surface area, amount and type of active surface oxygen species, oxidation state, and density of active sites are discussed. In addition, catalyst immobilization for practical air purification, reaction mechanism of formaldehyde oxidation, and the reaction parameters affecting the overall efficiency of the reaction are also reviewed.

PLncPRO for prediction of long non-coding RNAs (lncRNAs) in plants and its application for discovery of abiotic stress-responsive lncRNAs in rice and chickpea.

Abstract: Long non-coding RNAs (lncRNAs) make up a significant portion of non-coding RNAs and are involved in a variety of biological processes. Accurate identification/annotation of lncRNAs is the primary step for gaining deeper insights into their functions. In this study, we report a novel tool, PLncPRO, for prediction of lncRNAs in plants using transcriptome data. PLncPRO is based on machine learning and uses random forest algorithm to classify coding and long non-coding transcripts. PLncPRO has better prediction accuracy as compared to other existing tools and is particularly well-suited for plants. We developed consensus models for dicots and monocots to facilitate prediction of lncRNAs in non-model/orphan plants. The performance of PLncPRO was quite better with vertebrate transcriptome data as well. Using PLncPRO, we discovered 3714 and 3457 high-confidence lncRNAs in rice and chickpea, respectively, under drought or salinity stress conditions. We investigated different characteristics and differential expression under drought/salinity stress conditions, and validated lncRNAs via RT-qPCR. Overall, we developed a new tool for the prediction of lncRNAs in plants and showed its utility via identification of lncRNAs in rice and chickpea.

Global transcriptome and coexpression network analyses reveal cultivar-specific molecular signatures associated with seed development and seed size/weight determination in chickpea

Abstract: Seed development is an intricate process regulated via a complex transcriptional regulatory network. To understand the molecular mechanisms governing seed development and seed size/weight in chickpea, we performed a comprehensive analysis of transcriptome dynamics during seed development in two cultivars with contrasting seed size/weight (small-seeded, Himchana 1 and large-seeded, JGK 3). Our analysis identified stage-specific expression for a significant proportion (>13%) of the genes in each cultivar. About one half of the total genes exhibited significant differential expression in JGK 3 as compared with Himchana 1. We found that different seed development stages can be delineated by modules of coexpressed genes. A comparative analysis revealed differential developmental stage specificity of some modules between the two cultivars. Furthermore, we constructed transcriptional regulatory networks and identified key components determining seed size/weight. The results suggested that extended period of cell division during embryogenesis and higher level of endoreduplication along with more accumulation of storage compounds during maturation determine large seed size/weight. Further, we identified quantitative trait loci-associated candidate genes harboring single nucleotide polymorphisms in the promoter sequences that differentiate small- and large-seeded chickpea cultivars. The results provide a valuable resource to dissect the role of candidate genes governing seed development and seed size/weight in chickpea.

Graphene Oxide-Coated Surface: Inhibition of Bacterial Biofilm Formation due to Specific Surface–Interface Interactions

Abstract: Graphene oxide (GO) is a promising and remarkable nanomaterial that exhibits antimicrobial activity due to its specific surface–interface interactions. In the present work, for the first time, we have reported the antibacterial activity of GO-coated surfaces prepared by two different methods (Hummers’ and improved, i.e., GOH and GOI) against bacterial biofilm formation. The bacterial toxicity of the deposited GO-coated surfaces was investigated for both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) models of bacteria. The mechanism of inhibition is different on the coated surface than that in suspension, as determined by measurement of the percentage inhibition of biofilm formation, Ellman’s assay, and colony forming unit (CFU) studies. The difference in the nature, degree of oxidative functionalities, and size of the synthesized GO nanoparticles mitigates biofilm formation. To better understand the antimicrobial mechanism of GO when coated on surfaces, we were able to demonst...

Reciprocal carbonyl-carbonyl interactions in small molecules and proteins

Abstract: Carbonyl-carbonyl n→π* interactions where a lone pair (n) of the oxygen atom of a carbonyl group is delocalized over the π* orbital of a nearby carbonyl group have attracted a lot of attention in recent years due to their ability to affect the 3D structure of small molecules, polyesters, peptides, and proteins. In this paper, we report the discovery of a "reciprocal" carbonyl-carbonyl interaction with substantial back and forth n→π* and π→π* electron delocalization between neighboring carbonyl groups. We have carried out experimental studies, analyses of crystallographic databases and theoretical calculations to show the presence of this interaction in both small molecules and proteins. In proteins, these interactions are primarily found in polyproline II (PPII) helices. As PPII are the most abundant secondary structures in unfolded proteins, we propose that these local interactions may have implications in protein folding.Carbonyl-carbonyl π* non covalent interactions affect the structure and stability of small molecules and proteins. Here, the authors carry out experimental studies, analyses of crystallographic databases and theoretical calculations to describe an additional type of carbonyl-carbonyl interaction.

Real-time water quality monitoring system using Internet of Things

Abstract: The conventional method of testing water quality is to gather samples of water manually and send to the lab to test and analyze. This method is time consuming, wastage of man power, and not economical. The water quality measuring system that we have implemented checks the quality of water in real time through various sensors (one for each parameter: pH, conductivity, temperature) to measure the quality of water. The ZigBee module in the system transfers data collected by the sensors to the microcontroller wirelessly, and a GSM module transfers wirelessly the data further from the microcontroller to the smart phone/PC. The system also has proximity sensors to alert the officials by sending a message to them via the GSM module in case someone tries to pollute the water body. This system can keep a strict check on the pollution of the water resources and be able to provide an environment for safe drinking water.

Understanding the Li-storage in few layers graphene with respect to bulk graphite: experimental, analytical and computational study

Abstract: In order to understand, clarify and provide confirmations in the contexts of the prevalent confusions concerning Li-storage in graphenic carbon (viz. the reduced dimensional scale of graphitic carbon), electrochemical lithiation/delithiation has been performed with CVD-grown fairly pristine well-ordered few-layer graphene films (FLG; ∼7 layers; as a model material). Chronopotentiograms and cyclic voltammograms recorded with the FLG present distinct features corresponding to the transformation between different Li-GICs (i.e., ‘staging’) below 0.3 V against Li/Li+, thus confirming that ‘classical’ Li-intercalation does occur even at such reduced dimensional (nano)scale. Nevertheless, even in this lower potential window (our main focus here), Li-storage in FLG involves contributions from both diffusion- and surface-controlled mechanisms. The Li-capacities recorded with FLG just within this lower potential window, and also upon subtracting any possible contribution from the Cu current collector, were still ∼3–4 times greater than those obtained with similarly grown thicker bulk graphite films (TBG: ∼450 nm; Li-capacity recorded: ∼380 mA h g−1). Contrary to the usual belief, the excess Li-capacity of FLG cannot be explained by the presence of extrinsic/intrinsic defects, which are nearly negligible in the FLG films under consideration. Simulation of Li-storage in graphene via DFT indicated that the excess capacity (after formation of the LiC6 configuration) is associated with additional stable Li-storage on the outer graphene surfaces in the forms of more than one Li-layer (but different from Li-plating) and segregation close to the ‘stepped’ (exposed) edges of the inner graphene layers (but not exactly at the edge sites). Overall, such predicted Li-storage mechanisms are in agreement with the experimentally observed contributions from both ‘classical’ Li-intercalation and surface-controlled processes (even at potentials below 0.3 V), which primarily account for the excess Li-capacities recorded with graphenic carbon.

Identification, Characterization, and Functional Validation of Drought-responsive MicroRNAs in Subtropical Maize Inbreds.

Abstract: MicroRNA-mediated gene regulation plays a crucial role in controlling drought tolerance In the present investigation, 13 drought-associated miRNA families consisting of 65 members and regulating 42 unique target mRNAs were identified from drought-associated microarray expression data in maize and were subjected to structural and functional characterization The largest number of members (14) was found in the zma-miR166 and zma-miR395 families, with several targets However, zma-miR160, zma-miR390, zma-miR393 and zma-miR2275 each showed a single target Twenty-three major drought-responsive cis-regulatory elements were found in the upstream regions of miRNAs Many drought-related transcription factors, such as GAMYB, HD-Zip III and NAC, were associated with the target mRNAs Furthermore, two contrasting subtropical maize genotypes (tolerant: HKI-1532 and sensitive: V-372) were used to understand the miRNA-assisted regulation of target mRNA under drought stress Approximately 35% and 31% of miRNAs were up-regulated in HKI-1532 and V-372, respectively The up-regulation of target mRNAs was as high as 142% in HKI-1532 but was only 238% in V-372 The expression patterns of miRNA-target mRNA pairs were classified into four different types: Type I- up-regulation, Type II- down-regulation, Type III- neutral regulation and Type IV- opposite regulation HKI-1532 displayed 46 Type I, 13 Type II and 23 Type III patterns, whereas V-372 had mostly Type IV interactions (151) A low level of negative regulations of miRNA associated with a higher level of mRNA activity in the tolerant genotype helped to maintain crucial biological functions such as ABA signaling, the auxin response pathway, the light-responsive pathway and endosperm expression under stress conditions, thereby leading to drought tolerance Our study identified candidate miRNAs and mRNAs operating in important pathways under drought stress conditions, and these candidates will be useful in the development of drought-tolerant maize hybrids

Role of exchange protein directly activated by cAMP (EPAC1) in breast cancer cell migration and apoptosis

Abstract: Despite the current progress in cancer research and therapy, breast cancer remains the leading cause of mortality among half a million women worldwide. Migration and invasion of cancer cells are associated with prevalent tumor metastasis as well as high mortality. Extensive studies have powerfully established the role of prototypic second messenger cAMP and its two ubiquitously expressed intracellular cAMP receptors namely the classic protein kinaseA/cAMP-dependent protein kinase (PKA) and the more recently discovered exchange protein directly activated by cAMP/cAMP-regulated guanine nucleotide exchange factor (EPAC/cAMP-GEF) in cell migration, cell cycle regulation, and cell death. Herein, we performed the analysis of the Cancer Genome Atlas (TCGA) dataset to evaluate the essential role of cAMP molecular network in breast cancer. We report that EPAC1, PKA, and AKAP9 along with other molecular partners are amplified in breast cancer patients, indicating the importance of this signaling network. To evaluate the functional role of few of these proteins, we used pharmacological modulators and analyzed their effect on cell migration and cell death in breast cancer cells. Hence, we report that inhibition of EPAC1 activity using pharmacological modulators leads to inhibition of cell migration and induces cell death. Additionally, we also observed that the inhibition of EPAC1 resulted in disruption of its association with the microtubule cytoskeleton and delocalization of AKAP9 from the centrosome as analyzed by in vitro imaging. Finally, this study suggests for the first time the mechanistic insights of mode of action of a primary cAMP-dependent sensor, Exchange protein activated by cAMP 1 (EPAC1), via its interaction with A-kinase anchoring protein 9 (AKAP9). This study provides a new cell signaling cAMP-EPAC1-AKAP9 direction to the development of additional biotherapeutics for breast cancer.

Electrochemical Formation of FeV(O) and Mechanism of Its Reaction with Water During O-O Bond Formation

Abstract: A detailed electrochemical investigation of a series of iron complexes (biuret-modified tetraamido iron macrocycles FeIII -bTAML), including the first electrochemical generation of FeV (O), and demonstration of their efficacy as homogeneous catalysts for electrochemical water oxidation (WO) in aqueous medium are reported. Spectroelectrochemical and mass spectral studies indicated FeV (O) as the active oxidant, formed due to two redox transitions, which were assigned as FeIV (O)/FeIII (OH2 ) and FeV (O)/FeIV (O). The spectral properties of both of these high-valent iron oxo species perfectly match those of their chemically synthesised versions, which were thoroughly characterised by several spectroscopic techniques. The O-O bond-formation step occurs by nucleophilic attack of H2 O on FeV (O). A kinetic isotope effect of 3.2 indicates an atom-proton transfer (APT) mechanism. The reaction of chemically synthesised FeV (O) in CH3 CN and water was directly probed by electrochemistry and was found to be first-order in water. The pKa value of the buffer base plays a critical role in the rate-determining step by increasing the reaction rate several-fold. The electronic effect on redox potential, WO rates, and onset overpotential was studied by employing a series of iron complexes. The catalytic activity was enhanced by the presence of electron-withdrawing groups on the bTAML framework. Changing the substituents from OMe to NO2 resulted in an eightfold increase in reaction rate, while the overpotential increased threefold.

Effects of ionic liquids on the nanoscopic dynamics and phase behaviour of a phosphatidylcholine membrane

Abstract: Ionic liquids (ILs) are potential candidates for new antimicrobials due to their tunable antibacterial and antifungal properties that are required to keep pace with the growing challenge of bacterial resistance. To a great extent their antimicrobial actions are related to the interactions of ILs with cell membranes. Here, we report the effects of ILs on the nanoscopic dynamics and phase behaviour of a dimyristoylphosphatidylcholine (DMPC) membrane, a model cell membrane, as studied using neutron scattering techniques. Two prototypical imidazolium-based ILs 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM[BF4]) and 1-decyl-3-methylimidazolium tetrafluoroborate (DMIM[BF4]), which differ only in terms of the alkyl chain length of cations, have been used for the present study. Fixed Elastic Window Scan (FEWS) shows that the incorporation of ILs affects the phase behaviour of the phospholipid membrane significantly and the transition from a solid gel to a fluid phase shifts to lower temperature. This is found to be consistent with our differential scanning calorimetry measurements. DMIM[BF4], which has a longer alkyl chain cation, affects the phase behaviour more strongly in comparison to BMIM[BF4]. The pressure–area isotherms of the DMPC monolayer measured at the air–water interface show that in the presence of ILs, isotherms shift towards higher area-per lipid molecule. DMIM[BF4] is found to shift the isotherm to a greater extent compared to BMIM[BF4]. Quasielastic neutron scattering (QENS) data show that both ILs act as a plasticizer, which enhances the fluidity of the membrane. DMIM[BF4] is found to be a stronger plasticizing agent in comparison to BMIM[BF4] that has a cation with a shorter alkyl chain. The incorporation of DMIM[BF4] enhances not only the long range lateral motion but also the localised internal motion of the lipids. On the other hand, BMIM[BF4] acts weakly in comparison to DMIM[BF4] and mainly alters the localised internal motion of the lipids. Any subtle change in the dynamical properties of the membrane can profoundly affect the stability of the cell. Hence, the dominant effect of the IL with the longer chain length on the dynamics of the phospholipid membrane might be correlated with its cytotoxic activity. QENS data analysis has provided a quantitative description of the effects of the two imidazolium-based ILs on the dynamical and phase behaviour of the model cell membrane, which is essential for a detailed understanding of their action mechanism.

Impact of Self-Trapped Excitons on Blue Photoluminescence in TiO2 Nanorods on Chemically Etched Si Pyramids

Abstract: Temperature-dependent photoluminescence (PL) of titanium oxide (TiO2) shows an evolution of blue emission when exposed to 50 keV Ar+ ions. The origin of observed PL has been examined by X-ray absorption near-edge spectroscopy (XANES) at Ti-K,L and O-K edges, revealing the reduction of ligand field splitting owing to the formation of oxygen vacancies (OVs) by destroying TiO6 octahedral symmetry. Detailed PL and XANES analyses suggest that the fluence (ions/cm2) dependent increase in OVs not only boosts the conduction electrons but also increases the density of holes in localized self-trapped exciton (STE) states near the valence band. Based on these observations, we propose a model in which doped conduction electrons are recombining radiatively with the holes in STE states for blue light emission.

Evaluation of Odd–Even Day Traffic Restriction Experiments in Delhi, India

Abstract: During periods from January 1 to January 15 and April 15 to April 30, 2016, the Government of the National Capital Territory of Delhi, India, implemented an odd–even vehicle rule. Under this rule, between 08:00 and 20:00, only cars with even-numbered plates were allowed to operate on even-numbered dates of the calendar and only cars with odd-numbered plates on odd-numbered dates. In light of the varying experiences of vehicle restriction practices from around the world, this study evaluated the effects of both phases of the odd–even policy on transport patterns and vehicle use in Delhi. Observational surveys were carried out at four locations in Delhi to observe traffic flow and vehicle occupancy data. Speed data were extracted for 38 origin–destination pairs during the January phase and for 66 pairs for the April phase, with a sample of roads from all over Delhi and with Google Maps API (application programming interface) software. During the experimental periods, car flow rates on roads were reduced by ...

Impact of Cl Doping on Electrochemical Performance in Orthosilicate (Li2FeSiO4): A Density Functional Theory Supported Experimental Approach

Abstract: Safe and high-capacity cathode materials are a long quest for commercial lithium-ion battery development. Among various searched cathode materials, Li2FeSiO4 has taken the attention due to optimal working voltage, high elemental abundance, and low toxicity. However, as per our understanding and observation, the electrochemical performance of this material is significantly limited by the intrinsic low electronic conductivity and slow lithium-ion diffusion, which limits the practical capacity (a theoretical value of ∼330 mAh g-1). In this report, using first-principles density functional theory based approach, we demonstrate that chlorine doping on oxygen site can enhance the electronic conductivity of the electrode and concurrently improve the electrochemical performance. Experimentally, X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission gun scanning electron microscopy elemental mapping confirms Cl doping in Li2-xFeSiO4-xClx/C (x ≤ 0.1), while electrochemical cycling performance demonstrated improved performance. The theoretical and experimental studies collectively predict that, via Cl doping, the lithium deinsertion voltage associated with the Fe2+/Fe3+ and Fe3+/Fe4+ redox couples can be reduced and electronic conductivity can be enhanced, which opens up the possibility of utilization of silicate-based cathode with carbonate-based commercial electrolyte. In view of potential and electronic conductivity benefits, our results indicate that Cl doping can be a promising low-cost method to improve the electrochemical performance of silicate-based cathode materials.

Dually crosslinked injectable hydrogels of poly(ethylene glycol) and poly[(2-dimethylamino)ethyl methacrylate]-b-poly(N-isopropyl acrylamide) as a wound healing promoter.

Abstract: Rapid gelation, low heat generation, biocompatibility, biodegradability, avoiding the use of a small molecular weight gelator and high gel fraction are the essential criteria for the successful biomedical application of an injectable hydrogel We have developed a series of dually crosslinked injectable hydrogels of PEG and poly[2-(dimethylamino)ethyl methacrylate]-b-poly(N-isopropyl acrylamide) through extremely simple chemistry The sequential nucleophilic substitution reaction between PEG containing reactive termini and the copolymer provided chemically crosslinked hydrogels with a gel fraction as high as 96–99% with a gelation time of 1–4 min under physiological conditions The gelation occurred with ca 1 °C rise in temperature per gram of the injectable solution, avoids formation of by-products and can be performed in the temperature range of 20–37 °C The hydrogels undergo hardening at a physiological temperature as confirmed by rheological experiments The gelation time, water swelling, mechanical properties and degradability of the hydrogels depend on the PEG to copolymer ratio in the injectable solution The rheological behaviour of the fully hydrated hydrogels showed desirable mechanical properties for soft tissue regeneration The hydrogels exhibited blood compatibility and retained the viability of HepG2 cells with time Platelet adhesion and aggregation followed by fibrinogen adsorption ability makes these hydrogels suitable for wound healing applications

A versatile carbohydrate based gelator for oil water separation, nanoparticle synthesis and dye removal

Abstract: A versatile green gelator suitable for multiple applications is reported. Gelation of organic solvents in a significantly low gelation time (<5 s) is achieved. The effect of cooling and sonication on gelation time is investigated. Apart from organic solvents, the gelator is capable of forming gels with fuel oils such as diesel and petrol also; therefore, it has been utilized for the separation of oil from an oil/water mixture through selective gelation of the oil. The gelator was also found to be capable of forming hydrogels through rational control of the reaction conditions. Hydrogel prepared using the gelator was further explored as reaction medium for the growth of gold nanoparticles. In the case of nanoparticle synthesis, the gelator served not only as a capping agent but also as a reducing agent. By taking advantage of the dual functionality of the gelator (capping and reducing agent), nanoparticles of both gold and silver were prepared in fluid medium also. The organogel, prepared using toluene and gelator, was utilized for the removal of the waterborne synthetic dye rhodamine B.

Selective C-H Bond Oxidation Catalyzed by the Fe-bTAML Complex: Mechanistic Implications.

Abstract: Nonheme iron complexes bearing tetradentate N-atom-donor ligands with cis labile sites show great promise for chemoselective aliphatic C–H hydroxylation. However, several challenges still limit their widespread application. We report a mechanism-guided development of a peroxidase mimicking iron complex based on the bTAML macrocyclic ligand framework (Fe-bTAML: biuret-modified tetraamido macrocyclic ligand) as a catalyst to perform selective oxidation of unactivated 3° bonds with unprecedented regioselectivity (3°:2° of 110:1 for adamantane oxidation), high stereoretention (99%), and turnover numbers (TONs) up to 300 using mCPBA as the oxidant. Ligand decomposition pathways involving acid-induced demetalation were identified, and this led to the development of more robust and efficient Fe-bTAML complexes that catalyzed chemoselective C–H oxidation. Mechanistic studies, which include correlation of the product formed with the FeV(O) reactive intermediates generated during the reaction, indicate that the maj...

Experimental and theoretical analysis of a hybrid solar thermoelectric generator with forced convection cooling

Abstract: Hybrid solar thermoelectric generators (HSTEGs) have garnered significant research attention recently due to their potential ability to cogenerate heat and electricity. In this paper, theoretical and experimental investigations of the electrical and thermal performance of a HSTEG system are reported. In order to validate the theoretical model, a laboratory scale HSTEG system (based on forced convection cooling) is developed. The HSTEG consists of six thermoelectric generator modules, an electrical heater, and a stainless steel cooling block. Our experimental analysis shows that the HSTEG is capable of producing a maximum electrical power output of 4.7 W, an electrical efficiency of 1.2% and thermal efficiency of 61% for an average temperature difference of 92 °C across the TEG modules with a heater power input of 382 W. These experimental results of the HSTEG system are found to be in good agreement with the theoretical prediction. This experimental/theoretical analysis can also serve as a guide for evaluating the performance of the HSTEG system with forced convection cooling.

Twitter Stance Detection — A Subjectivity and Sentiment Polarity Inspired Two-Phase Approach

Abstract: The problem of stance detection from Twitter tweets, has recently gained significant research attention. This paper addresses the problem of detecting the stance of given tweets, with respect to given topics, from user-generated text (tweets). We use the SemEval 2016 stance detection task dataset. The labels comprise of positive, negative and neutral stances, with respect to given topics. We develop a two-phase feature-driven model. First, the tweets are classified as neutral vs. non-neutral. Next, non-neutral tweets are classified as positive vs. negative. The first phase of our work draws inspiration from the subjectivity classification and the second phase from the sentiment classification literature. We propose the use of two novel features, which along with our streamlined approach, plays a key role deriving the strong results that we obtain. We use traditional support vector machine (SVM) based machine learning. Our system (F-score: 74.44 for SemEval 2016 Task A and 61.57 for Task B) significantly outperforms the state of the art (F-score: 68.98 for Task A and 56.28 for Task B). While the performance of the system on Task A shows the effectiveness of our model for targets on which the model was trained upon, the performance of the system on Task B shows the generalization that our model achieves. The stance detection problem in Twitter is applicable for user opinion mining related applications and other social influence and information flow modeling applications, in real life.

The Dihydroxy Metabolite of the Teratogen Thalidomide Causes Oxidative DNA Damage

Abstract: Thalidomide [α-(N-phthalimido)glutarimide] (1) is a sedative and antiemetic drug originally introduced into the clinic in the 1950s for the treatment of morning sickness. Although marketed as entirely safe, more than 10 000 babies were born with severe birth defects. Thalidomide was banned and subsequently approved for the treatment of multiple myeloma and complications associated with leprosy. Although known for more than 5 decades, the mechanism of teratogenicity remains to be conclusively understood. Various theories have been proposed in the literature including DNA damage and ROS and inhibition of angiogenesis and cereblon. All of the theories have their merits and limitations. Although the recently proposed cereblon theory has gained wide acceptance, it fails to explain the metabolism and low-dose requirement reported by a number of groups. Recently, we have provided convincing structural evidence in support of the presence of arene oxide and the quinone-reactive intermediates. However, the ability ...

Oxidative dehydrogenation of C-C and C-N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds.

Abstract: Nitrogen heteroarenes form an important class of compounds which can be found in natural products, synthetic drugs, building blocks etc. Among the diverse strategies that were developed for the synthesis of nitrogen heterocycles, oxidative dehydrogenation is extremely effective. This review discusses various oxidative dehydrogenation strategies of C-C and C-N bonds to generate nitrogen heteroarenes from their corresponding heterocyclic substrates. The strategies are categorized under stoichiometric and catalytic usage of reagents that facilitate such transformations. The application of these strategies in the synthesis of nitrogen heteroarene natural products and synthetic drug intermediates are also discussed. We hope this review will arouse sufficient interest among the scientific community to further advance the application of oxidative dehydrogenation in the synthesis of nitrogen heteroarenes.

Mental illness and injuries: emerging health challenges of urbanisation in South Asia.

Abstract: Rapid unplanned urbanisation in South Asia has overlooked the health needs of poor and marginalised people. Devaki Nambiar and colleagues examine the problems of mental illness and injuries, and call for renewed political and financial commitment to urban health