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Observations of the 21 cm Hi line from the milky way galaxy using pyramidal horn radio telescope
(Springer Nature, 2026-10-13)
Bhattacharjee, Kaustav
;
Grover, Himanshu
;
Arumugam, P
We present the design, implementation, and operation of a pyramidal horn radio telescope built for detecting the Galactic 21 cm neutral hydrogen line emission. The system employs a Software-Defined Radio (SDR) based pipeline to obtain drift-scan observations, which were calibrated and processed to generate Hi sky maps, a Galactic rotation curve and spiral arm features. This demonstrates that this low-cost system is effective both for educational purposes and scientific exploration of Galactic structure at radio frequencies.
Detection of the Cosmological 21 cm Signal in Autocorrelation at z ∼ 1 with the Canadian Hydrogen Intensity Mapping Experiment
(American Astronomical Society, 2026-09-28)
Amiri, Mandana
;
Bandura, Kevin
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Chakraborty, Arnab
;
Cliche, Jean-François
;
Dobbs, Matt
We present the first detection of the cosmological 21 cm intensity mapping signal in autocorrelation at z ∼ 1 with the Canadian Hydrogen Intensity Mapping Experiment (CHIME). Using 94 nights of observation, we have measured the 21 cm auto power spectrum over a frequency range of 608.2–707.8 MHz (z = 1.34–1.01) at 0.4 h Mpc−1 ≲ k ≲ 1.5 h Mpc−1, with a detection significance of 12.4σ. Our analysis employs significant improvements to the CHIME data processing pipeline compared to previous work, including novel radio frequency interference detection and masking algorithms, achromatic beamforming techniques, and foreground filtering before time averaging to minimize spectral leakage. We establish the robustness and reliability of our detection through a comprehensive suite of validation tests. We also measure the 21 cm signal in two independent sub-bands centered at z ∼ 1.08 and z ∼ 1.24 with detection significance of 8.6σ and 9.1σ, respectively. We briefly discuss the theoretical interpretation of these measurements in terms of a power spectrum model, deferring the details to a companion paper. This auto power spectrum detection demonstrates CHIME’s capability to probe large-scale structure through 21 cm intensity mapping without reliance on external galaxy surveys.
Columnar self-assembly as a design strategy for naphthophenanthridine-based blue OLEDs
(Royal Society of Chemistry (RSC), 2026-07-30)
Bhat S, Vanishree
;
Danjou, Pierre-Edouard
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Kumar, Anil
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Duponchel, Benoit
;
Depriester, Michael
Columnar materials have lately emerged as promising materials for organic light-emitting diodes (OLEDs) owing to their unidirectional charge transport and self-assembly characteristics. In the present investigation, we report the synthesis of naphthophenanthridine-based columnar dimers with varying peripheral alkyl chain lengths (CnH2n+1; n = 4, 8, and 12), emphasising a strategic design of materials for blue OLEDs. Polarised optical microscopy and X-ray diffraction studies reveal that the dimers exhibited a columnar soft-crystalline phase. This behaviour can be ascribed to the strong π-conjugation in the naphthophenanthridine, which facilitates the rigid columnar aggregation. Exhibiting charge-carrier mobility of the order of 10−5 cm2 V−1 s−1, and favourable emission characteristics, these dimers are appropriate for light-emitting applications. Using one of the homologs, blue OLEDs have been fabricated, which demonstrated an external quantum efficiency of 2.2% and a maximum luminance of 1153 cd m−2. The moderate device efficiency is attributed to the relatively deep HOMO level and suboptimal charge balance, highlighting opportunities for further molecular and device engineering to elevate OLED performance.
Passive and Active Mechanical Responses of Axons
(Raman Research Institute, 2026-05-01)
Veer,Sukh
Probing symmetry-driven DEA dynamics in ozone investigated by velocity slice imaging technique
(AIP Publishing LLC, 2026-10-01)
Varghese, Melvin
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Dharun, J
;
Mason, Nigel J
;
Krishnakumar, E
;
Prabhudesai, Vaibhav S
We report the results of a comprehensive experimental investigation of dissociative electron attachment (DEA) to ozone using the velocity slice imaging technique. We reveal several channels that yield both O^− and O^−2 from negative-ion resonances formed by electron attachment. Our results demonstrate that DEA to ozone proceeds through competition between symmetric and asymmetric dissociation pathways. This is governed by excitation of symmetric, asymmetric, and bending vibrational modes and likely involves vibronic coupling between the symmetry of the negative ion resonance states. At 1.6 eV, symmetric dissociation results in vibrationally excited O2 and O^−2 with near-thermal kinetic energies. An additional asymmetric dissociation pathway driven by overlapping contributions from ^2A1 and ^2 B2 states producing rotationally excited O2 with enhanced translational energy is identified. DEA from the second resonance yields both O^− and O^−2 with considerable internal energies arising from a single anionic state (^2B2) proceeding via an asymmetric dissociation mechanism. In the 4.1 − 4.4 eV region, overlapping resonances with A1 and B2 symmetry lead to asymmetric dissociation, accompanied by a notable increase in internal excitations of the molecular moieties. This also provides experimental evidence for the previously proposed ^2A1 shape resonance at 4.2 eV. At higher energies around 6.9 eV, angular distribution analysis reveals a contribution from an additional ^2A1 state, in contrast to the theoretically predicted ^2B2 state. These findings establish a unified picture of competing symmetric and asymmetric dissociation mechanisms that produce highly internally excited and chemically reactive fragments.

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