Biomass-derived activated carbons (BACs) comprising highly porous structures and ultralightweight characteristics are potential microwave-absorbing materials (MAMs). Here, we report diverse BACs from rice stubble (PAAC), bajra husk (BJAC), royal palm leaves (RAC) and amla leaves (ACA) prepared via a two-step process involving carbonisation and KOH activation. The superimposed effect of natural hierarchical structure and activation results in exceptionally large specific surface area i.e., PAAC (1744.6 m2/g), ACA (1704 m2/g), BJAC (1613.5 m2/g) and RAC (1315 m2/g), enabling optimal balance the relatively adverse relationship between dielectric loss and impedance matching to attain effective microwave (MW) absorption. At minimal loading, PAAC10 achieves remarkably strong reflection loss (RLmin) of -69 dB with an effective absorption bandwidth (EABmax) of 4.4 GHz covering 75 % of the Ku band at 1.66 mm thickness. RAC20 exhibits an EABmax of 5 GHz at 1.67 mm, spanning 83.3 % of the Ku band. BJAC15 demonstrates an exceptional EABmax of 6.1 GHz, covering the entire Ku band at 2.2 mm, and 4.16 GHz spanning the whole X-band at 3.1 mm. The activation-induced hierarchical 3D porous conductive network enhances electromagnetic wave (EMW) scattering, interfacial polarization, and conductive losses. Simultaneously, the incorporation of oxygen-containing functional groups induces dipole polarization loss, contributing to a multi-component loss mechanism. Furthermore, by modulating dielectric properties and impedance matching through controlled material loading, BACs exhibit superior MW absorption with strong RL and ultra-broad EAB at minimal thicknesses. These findings provide valuable insights into the potential of BACs as high-performance, lightweight MAMs for advanced EMW absorbing applications.

A green, catalyst free, one-pot, gram scale microwave-assisted synthesis of fluorescent furo [3,2-c]quinolone nucleoside analogues has been successfully developed using 2-Me-THF as a greener solvent. This method, employing 3 ',5 '-di-O-acetyl-5-formyl-2 '-deoxyuridine, alkyl isocyanides, and differently substituted 4-hydroxyquinolones, achieved product yield up to 92 %, which offers high atom economy, reduced reaction time and simple work-up procedure. The products were fully characterized by spectroscopic techniques and single crystal X-ray analysis with DFT analysis conforming the electronic structures. Fluorescence studies revealed strong emission (similar to 450 nm), large Stokes shifts (59-98 nm), and high quantum yields (0.053-0.595). Solvatochromism studies highlighted their environmental sensitivity, indicating potential applications in nucleic acid research and bio-imaging.

Lithium-based electrolytes are, at least from a thermodynamic standpoint, the most suitable ion-transport materials for energy storage systems. However, lithium-based ionic conductors suffer from safety concerns, and the limited availability of lithium in the Earth’s crust is at the root of the need to consider alternative metal ions. Notably, sodium stands out as the sixth most-prevalent element; therefore, when considering mineral reserves, it as a very attractive candidate as an alternative to the status quo. Even if the specific energy and energy density of sodium are indeed inferior with respect to those of lithium, there is substantial economic appeal in promoting the use of the former metal in stationary energy storage applications. For these reasons, the promise of sodium is likely to extend to other commercial applications, including portable electronics, as well as hybrid and electric vehicles. Widely used organic liquid electrolytes, regardless of their chosen metal cation, are disadvantageous due to leakage, evaporation, and high flammability. Polymer electrolytes are acknowledged as the most effective candidates to overcome these obstacles and facilitate the advancement of next-generation energy storage applications. In this contribution, an in-depth and comprehensive review of sodium polymer electrolytes for primary and secondary batteries is proposed. The overarching goal was to gain insight into successful synthetic strategies and their implications for conduction parameters and conductivity mechanisms. The focus lies on solid, gel, and composite polymer electrolytes. Our hope is that the proposed discussion will be helpful to all operators in the field, whether in tackling fundamental research problems or resolving issues of practical significance.

The requirement in resolving electromagnetic (EM) problems in stealth warhead technologies are excellent absorption ability, lightweight, and thin dimensions. In this direction, this study provides a straightforward hydrothermal one-pot method to synthesize superparamagnetic Mn-based ferrite co-doped with Co and Cu (MCCF), and the article presents its microwave absorption properties. Using cutting-edge techniques, the MCCF nanocomposite phase structure, morphological, superparamagnetic, and microwave absorption properties were measured and analyzed. MCCF-822 ferrite shows superparamagnetic properties simultaneously with a high M-s value 71.4 emu/g. Vector network analysis of MCCF-822 with 70 wt% loading demonstrates an effective absorption bandwidth (EAB) of 5.2 GHz with a maximum reflection loss (RLmax) of -19.2 dB at 2 mm thickness, and it spans almost 92.77 % frequency region (3.3-18 GHz range with RL < -10 dB) by varying thickness 1.7 mm-6 mm. At 60 wt% loading, it covers the whole X & K-u band with a thickness range from 2 to 9 mm with a good EAB of 4.3 GHz at 2.5 mm thickness with RLmax of -16 dB. The dual absorption bands are also present in MCCF-613, which increases the EAB with RLmax -52.99 dB at 9 mm, fulfilling the superparamagnetic properties. Thus, MCCF-822 is proposed as a cost-effective superior ferrite nanocomposite for microwave absorption applications.

The promise of sodium-ion conducting polymer electrolytes in rechargeable power sources is yet to be fulfilled. The possibility to combine the very attractive physical-chemical properties of perfluorinated polyethers (PFPEs) with sodium salts has not thus far been considered. Here we investigate a series of eight plasticized polymer electrolytes based on an alpha,omega-terminated poly[PFPE-block-PEO] (hereafter called PEG-PFPE-PEG), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), and dimethyl sulfoxide (DMSO) as plasticizer, having general formula PEG-PFPE-PEG/(NaTF-SI)(x)(DMSO)(y) (0.004 <= x <= 0.610, 3.205 <= y <= 3.794). The thermal analysis results, carried out by means of DSC, indicate that the plasticizer remains intimately integrated in the polymer electrolytes up to the decomposition temperature of PEG-PFPE-PEG (180 degrees C ca.) and is not significantly released out of the polymer hosts in closed cells. The vibrational investigation, carried out by FT-IR spectroscopy in the medium IR region, shed light on NaTFSI-PEG-PFPE-PEG-DMSO interactions. In particular, the role of the OH functional groups in facilitating salt dissolution was elucidated, along with that of the CO and CF moieties. The ionic conductivity was investigated by impedance spectroscopy, in the frequency interval 100 mHz to 1 MHz. The conductivity at 25 degrees C is as high as 8.0 x 10(-4) S center dot cm(-1). Three of at least five polarization events (one electrode and four interdomain polarizations in total) were fully resolved and were associated with different interfacing domains in the polymer electrolytes with increasing DMSO content. The behavior of the corresponding conductivities and frequencies were fitted with Vogel-Tamman-Fulcher (VTF) and Arrhenius equations, respectively, highlighting the concomitant roles of segmental motion and ionic hopping in these hybrid systems. Furthermore, it was shown that the presence of DMSO, a wellknown cryodepressant, significantly decreases the glass transition temperature of the electrolytes.

Sodium‐containing ionic liquids are very promising candidates as ion‐conducting materials in alternative to electrolytes based on lithium chemistry. Here we investigate a series of seven ionic liquids with formula (EMImCl/(AlCl3)1.5)/(δ‐NaCl)x (0≤x≤0.74). The salt is comprised of a disordered form of NaCl prepared by metalorganic synthesis, which assures faster dissolution in high concentration. The vibrational investigation carried out by FT‐IR spectroscopy in the medium IR region shed light on salt‐IL interactions. The ionic conductivity was investigated by Broadband Electric Spectroscopy. The direct current conductivity (σdc) profiles versus the reciprocal temperature exhibited a Vogel‐Tamman‐Fulcher behavior indicating the assistance of micro‐Brownian motions to ionic migration. The value of σdc at 25 °C for x=0.74 was found to be 1.2×10−2 S cm−1. Reversible deposition of Na and Al‐containing species take place with high Coulombic efficiency (up to 97 %) and a high Na+ cation transport number (up to 0.95). The understanding of ionic speciation was investigated in comparison with aqueous acid‐base systems exploring the benefits and limitations of such analogy. The role of a Grotthuss‐type mechanism facilitating the exchange of chlorides between acidic catenated chloroaluminate species in anionic domains of the ILs is considered.

Various materials are being explored to efficiently work either as microwave (MW) absorbing material or EMI shielding materials. In the present study, we have reported a bifunctional composite material made by growing MWCNTs on waste biomass derived activated carbon (ACNT), which can be used for both microwave absorption and EMI shielding applications. The ACNT at 10 wt% (ACNT10) filler loading demonstrated an effective absorption bandwidth (EAB) of 5.8 GHz at 1.98 mm thickness which covered 96.6% of K-u band, whereas at 2.85 mm thickness it covered entire X band (8-12.25 GHz). A maximum reflection loss (RLmax) of -27.6 dB at 16.16 GHz was achieved by ACNT10 at 1.83 mm thickness. At the same time by increasing ACNT loading to 25 wt%, the increase in conductivity and charge transport was observed, due to which ACNT25 displayed an outstanding EMI shielding performance and achieved total EMI shielding effectiveness (SET) of 137 dB. Thus, by tuning the loading of ACNT, the absorber material can be converted from MW absorption to high performance EMI shielding material.

In this study, in situ-grown cobalt ferrite (CoFe2O4, CF) nanoparticles on waste biomass-derived porous activated carbon (AC) were grown via a facile hydrothermal technique to develop a CF/AC nanocomposite.

Microwave absorbing materials have become an important component in electronics, communication, and modem warfare. The present study reports porous activated carbon derived from mango leaves biomass and by facile method of carbonization and activation. The porous activated carbon has the potential to become an efficient microwave absorbing material. The SEM and FESEM images dearly showed the porous structure which was further confirmed using BET analysis. The sample having 20 wt% loading of activated carbon in paraffin wax gave the Highest Reflection Loss (RLmax) of -23.26 dB at 17.68 GHz & 1.50 mm thickness. The maximum effective absorption band width (i.e. reflection loss < -10 dB) of 5.17 GHz was obtained at 1.75 mm thickness, which covered 86.16% of Ku band. The effective absorption bandwidth of 3.31 GHz was also obtained at 2.5 mm thickness which covered 82.75% of X band. This excellent microwave absorption property was obtained by high impedance matching and subsequent attenuation of microwave by dielectric loss facilitated by the porous structure. This work provides a new source of biomass which is abundant in nature and can be easily processed as an enhanced microwave absorbing material having large effective absorption bandwidth at less thickness and low filler loading. (C) 2020 Elsevier B.V. All rights reserved.

A novel microwave absorbing composite medium for X-band (8 GHz-12GHz) is developed by mixing of core-shell consisting of carbon quantum dots (CQDs) coated barium titanate (BaTiO3) fibers with barium hexaferrite (BaFe12019) nanoparticles. CQDs are synthesized from agricultural waste using lemon peel as precursor material while the low density BaTiO3 fibers are synthesized via electro-spinning technique. The increase in diameter of BaTiO3 fibers as an effect of CQD coating has been confirmed using FESEM technique. The XRD and FTIR analysis of CQD coated BaTiO3 fibers are used to confirm the presence of carbon along with barium titanate. Composites based on BaFe12019 nanoparticles and CQD coated barium titanate (CQD@BaTiO3) fibers were developed by the ball-milling of BaFe12019 nanoparticles with CQD@BaTiO3 in different weight concentrations. The improved electrical permittivity of the BaFe12019 and CQD@BaTiO3 composites resulted in the increased reflection loss due to better impedance matching with the free space. The maximum reflection loss of -25.38 dB was achieved for composite containing 85% of BaFe12019 and 15% of CQD@BaTiO3, for a pellet of thickness 2.75 mm. Also, the maximum -10dB bandwidth (90% absorption) of the composite reaches to 2.7 GHz. (C) 2020 Elsevier B.V. All rights reserved.

An efficient approach has been made for the synthesis of a series of novel di alpha-aminophosphonates by the reaction of terephthalaldehyde with various pyrimidine/benzthiazole amines and diethyl phosphite using sulfonated graphitic carbon nitride - SA@g-C3N4 as catalyst under room temperature and solvent free conditions. Later, the different effects of these newly synthesized alpha-aminophosphonates as a function of concentration gradient has been scrutinized on the thermal and structural stability of stem bromelain (SBM) through combining the results of various spectroscopic techniques like UV-vis, steady state fluorescence and circular dichroism(CD). Lastly the competitive and distinctive behaviour of alpha-aminophosphonates towards the stability of SBM has been envisaged using molecular docking simulations which suggest that nature of alpha-aminophosphonates plays a crucial role for their interactions with SBM. Molecular docking results clearly show that alpha-aminophosphonates with pyrimidine ring are having more number of hydrogen bonding interaction with amino acid residues of SBM than alpha-aminophosphonates with benzthiazolyl ring. Sequentially for thermal and structure stability of SBM, concentration of alpha-aminophosphonates plays an inexorable role and through these results it must be concluded that most of the alpha-aminophosphonates are stabilizing the SBM upto the 0.1 mM concentration. (C) 2020 Elsevier B.V. All rights reserved.