5,991 research outputs found
India beyond sixty [leap forward] ; in memoriam Chowdhary Ranbir Singh
No full textContributed articles on Indian politics and governance and economic development in post-independence period; commemorating Ranbir Singh, Indian freedom fighter
Sentiment analysis of tweets using text and graph multi-views learning
No full textWith the surge of deep learning framework, various studies have attempted to address the challenges of sentiment analysis of tweets (data sparsity, under-specificity, noise, and multilingual content) through text and network-based representation learning approaches. However, limited studies on combining the benefits of textual and structural (graph) representations for sentiment analysis of tweets have been carried out. This study proposes a multi-view learning framework (end-to-end and ensemble-based) that leverages both text-based and graph-based representation learning approaches to enrich the tweet representation for sentiment classification. The efficacy of the proposed framework is evaluated over three datasets using suitable baseline counterparts. From various experimental studies, it is observed that combining both textual and structural views can achieve better performance of sentiment classification tasks than its counterparts
Characteristics of opinions in the societal and non-societal domains
No full textWith the increasing availability of user opinions on the web, understanding the distinct nature of opinions in societal and non-societal contexts becomes crucial for opinion mining and sentiment analysis tasks. Societal topics, encompassing social unrest, terrorist acts, and government policies, differ significantly from non-societal topics like product reviews, movie reviews, and restaurant reviews. Given the regional specificity of societal issues and the lack of sentiment-annotated resources for them, this paper highlights the need to comprehend the differences in opinions between these domains for effective sentiment analysis. Through statistical text and network analysis, it investigates word usage, sentiment word association, and homogeneity in societal versus non-societal contexts. The study also explores graph-based analysis as a novel approach to sentiment analysis, considering its advantage in easily expanding context through the addition of nodes, as opposed to the complexity of inserting relevant tokens in text. The findings suggest that while non-societal sentiment resources might not be directly applicable to societal domains, graph-based analysis offers promising avenues for sentiment analysis in diverse societal topics
3D structured small molecule acceptors with imide-linked perylene diimides on a 9,9'-spirobifluorene core for non-fullerene organic solar cells
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Molecular engineering of perylene-diimide-based polymer acceptors containing heteroacene units for all-polymer solar cells
No full textPolymer acceptors based on perylene diimide (PDI) with three symmetrical S-heteroacene backbone units of different sizes were synthesized for use in all-polymer solar cells (all-PSCs). The effects of varying the size of the heteroacene unit on the backbone of the PDI polymer are evident in the absorption spectra and their energy level offsets, which are correlated with their morphological and photovoltaic properties. These newly synthesized polymers were employed as acceptors with the polymer poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c]-[1,2,5]thiadiazole)] (PPDT2FBT) as the donor in all-PSCs that were found to exhibit modest power conversion efficiencies. The variations in photovoltaic properties of all-PSCs are investigated by characterizing the charge generation, carrier mobilities and recombination. The morphological disorder at the polymer/PPDT2FBT interface and average composition variations are revealed by using grazing incidence wide angle X-ray scattering (GIWAXS) and resonance soft X-ray scattering (R-SoXS) characterizations.11Nsciescopu
Excimer formation effects and trap-assisted charge recombination loss channels in organic solar cells of perylene diimide dimer acceptors
No full textGaining deep insight into the operative mechanism of organic photovoltaic (OPV) devices made of perylene-diimide (PDI) electron acceptors is challenging. Herein we perform a comparative study of three different solution-processable PDI-based heterojunctions for identifying the parameters limiting their OPV device performance. In all three systems the PTB7-Th polymer serves as the electron donor mixed with one of the three derivatives of the EP-PDI monomer, and the C6-PDI2 and BG-PDI2 dimers. The obtained power conversion efficiency (PCE) of these PTB7-Th:PDI systems is PCEEP-PDI = 3.65%, PCEC6-PDI2 = 5.36%, and PCEBG-PDI2 = 4.12%. Despite the existing major differences in the molecular structure of the PDI acceptors the electron transport properties of all three PTB7-Th:PDI layers remain in the same order of similar to 10(-6) cm(2) V-1 s(-1). The electron mobility is found to have an activation energy close to similar to 10kT thereby reflecting a high content of physical disorder in the three PDI acceptors. The endemic characteristic of trap-limited charge transport in PDI-based OPV layers is verified by (i) the dependence of open-circuit voltage on light intensity and (ii) the transient photovoltage characterization of the PTB7-Th:PDI devices. Based on GIWAXS measurements, the size of the well-ordered electron transporting domains in the OPV layers is between 4.0 and 6.8 nm, yet no evidence for PDI nanograin morphology features of the PDI multiadducts is found by scanning electron microscopy imaging. Photoluminescence spectroscopy reveals that all three PDI derivatives form emissive excimer-like states in the solid state, albeit with a different excimer stabilization energy. The losses induced by charge trapping are found to be increased in PTB7-Th:BG-PDI2, that is the derivative exhibiting the most stabilized excimer state and the smallest domain size. The optimum device efficiency of the C6-PDI2 heterojunction is attributed to its capability to form medium-sized electron transporting domains that are less disconnected by traps of disordered C6-PDI2 dimers. These findings signify the importance for PDI-dimer electron acceptors to maintain a three-dimensional configuration when used in OPV layers.11Nsciescopu
Propeller-shaped small molecule acceptors containing a 9, 9′-spirobifluorene core with imide-linked perylene diimides for non-fullerene organic solar cells
No full textThree-dimensional (3D) non-fullerene small molecule acceptors with imide-linked perylene diimides (iPDI) on a 9,90'-spirobi[9H-fluorene] core were designed, synthesized and characterized for use in organic solar cells. The best power conversion efficiency of 5.31% is obtained using SF-iPDI2 in a solution-processed bulk heterojunction solar cell. These results demonstrate that PDI derivatives with 3D molecular structures could serve as high-performance electron acceptors in non-fullerene solar cells.1112sciescopu
A Nonfullerene Small Molecule Acceptor with 3D Interlocking Geometry Enabling Efficient Organic Solar Cells
No full textA new 3D nonfullerene small-molecule acceptor is reported. The 3D interlocking geometry of the small-molecule acceptor enables uniform molecular conformation and strong intermolecular connectivity, facilitating favorable nanoscale phase separation and electron charge transfer. By employing both a novel polymer donor and a nonfullerene small-molecule acceptor in the solution-processed organic solar cells, a high-power conversion efficiency of close to 6% is demonstrated.1112690Nsciescopu
Control of the molecular geometry and nanoscale morphology in perylene diimide based bulk heterojunctions enables an efficient non-fullerene organic solar cell
No full textHerein we present the design of three perylene diimide (PDI) derivatives with different molecular geometries; namely the monomeric PDI1, the bay-linked PDI2 dimer, and the bay-linked PDI4 tetramer with a 9,9'-spirobifluorene core that are utilized as electron acceptors in non-fullerene organic solar cells (OSCs). In all cases the PTB7-Th polymer is used as the electron donor. Among the three PTB7-Th: PDI systems, the highest power conversion efficiency (PCE) is obtained by the PDI4-based OSC device that exhibits a maximum PCE = 6.44% followed by the PDI2-based (PCE = 5.32%) and PDI1-based (PCE = 2.48%) devices. The detailed study of the photoluminescence quenching, morphology and temperature-dependent charge transport properties of the three systems reveal that the highest PCE of PTB7-Th: PDI4 is a consequence of the three-dimensional (3D) molecular architecture of PDI4 that tunes energetic disorder in the PDI phase and contributes to the improvement of electron transport. Transient photovoltage characterization experiments further identify that the actual effect coming from the 3D molecular geometry of the PDI4 acceptor on PCE is the minimization of non-geminate charge recombination losses. This study provides updated guidelines for optimizing further the molecular structure of 3D small molecular electron acceptors that can be used in highly efficient non-fullerene OSCs.1121Nsciescopu
Grassroots climate resilience and sustainable agriculture in the Ranbir Singh Pura region of Jammu & Kashmir
No full textAbstract The study investigates grassroots climate resilience and sustainable agriculture in the Ranbir Singh Pura (R.S. Pura) region of Jammu and Kashmir, India a region known for premium Basmati rice cultivation yet characterised by severe climate vulnerability. Drawing on vulnerability analysis, resilience theory, climate adaptation, theory, and the multi-level perspective (MLP) on sustainability transitions, the research examines how marginal and small farmers perceive climate change, manage agricultural risks and implement adaptive practices within institutional and socio-economic constraints. Using a qualitative case study approach, data were collected through in-depth interviews, focus group discussions, and field observations across ten villages, capturing diverse experiences of climate impacts, adaptation measures and governance challenges. Findings reveal that farmers encounter increasing threats from erratic rainfall, groundwater depletion, pest outbreaks, hailstorms, and infrastructural deficits, resulting in yield instability and income volatility. While niche-level innovations such as the Suchetgarh Organic Basmati Rice Cluster demonstrate potential for enhancing resilience through organic farming, circular agricultural practices, and renewable energy integration, systemic barriers including inadequate policy support, low digital literacy, and limited financial access hamper the replication and scaling of such initiatives. The study highlights the risks of maladaptation particularly indiscriminate groundwater extraction and crop specialisation while advocating for integrated strategies combining sustainable agriculture, resource conservation and low-carbon energy transitions. Insights from the study are situated within the global literature to highlight the transformative potential of context-specific, multi-theoretical approaches in fostering resilient agricultural systems that can withstand the adverse consequences of climate change
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