@article {45361, title = { One pot ligand exchange method for a highly stable Au-SBA-15 catalyst and its room temperature CO oxidation}, journal = {Chemical Communications}, volume = {54}, year = {2018}, month = {NOV}, pages = {12412-12415}, type = {Article}, abstract = {A modified deposition precipitation (DP) method has been developed to address a fundamental issue of supporting well dispersed Au nanoparticles on silica. Ammonium chloride (NH4Cl) plays an important role in in situ modifying the gold precursor (HAuCl(4)3H(2)O) solution allowing facile deposition of gold NPs in the channels of SBA-15. The Au-SBA-15 catalyst (2.8 wt\%) synthesized by this procedure showed 100\% conversion for CO oxidation at room temperature with excellent stability at room temperature and high temperature.}, issn = {1359-7345}, doi = {10.1039/c8cc06887a}, author = {Soni, Yogita and Kavya, I. and Ajithkumar, T. G. and Vinod, C. P.} } @article {44553, title = {Preparation of colourless phosphate glass by stabilising higher Fe[II] in microwave heating}, journal = {Scientific Reports}, volume = {8}, year = {2018}, month = {APR}, pages = {6195}, abstract = {

Iron impurity in raw material remains a major challenge in producing colourless glass. In this investigation, we report microwave (MW) heating capable of altering Fe-redox ratio (Fe2+/Sigma Fe) enabling preparation of colourless phosphate glass. The effect of Sn concentration in retention of Fe[II] in glass melted in MW was compared with conventional glasses. Colourimetric study developing Fe2+-ferrozine colour complex reveals Fe-redox ratio \>= 0.49 required to obtain colourless phosphate glass. In microwave heating, addition of 1 wt.\% Sn metal powder can impart the desired effect whereas addition of 1.9 wt.\% Sn metal powder is required in conventional heating. The correlation equation of Fe-redox ratio with concentration of Sn metal is found to be different in microwave and conventional heating. Thus, exploiting this different redox changes in MW heating optical properties can be tailored. Preservation of higher Fe[II] in MW melted glass is also confirmed by XPS and TGA. P-31 MAS NMR spectra suggest that transition from cross linked ultra phosphate to linear polymer metaphosphate network in incorporation of Sn is found different in glass prepared adopting microwave irradiation. (27)A1 MAS NMR spectra suggest higher relative content of Al6+ in glass obtained from MW heating. Energy consumption analysis revels 3.4 kWh in MW heating while 14 kWh in conventional glass melting using resistance heating. Further, glass melting in MW can be completed within 2 h unlike similar to 5 h needed in conventional. MW heating plays a significant role in improving properties to make colourless phosphate glass in addition to significant energy and time saving.

}, issn = {2045-2322}, doi = {10.1038/s41598-018-24287-1}, author = {Mandal, Ashis K. and Mandal, B. and Illath, Kavya and Ajithkumar, T. G. and Halder, A. and Sinha, P. K. and Sen, Ranjan} } @article {44564, title = {Structural elucidation of NASICON (Na3Al2P3O12) based glass electrolyte materials: effective influence of boron and gallium}, journal = {RSC Advances}, volume = {8}, year = {2018}, pages = {14422-14433}, type = {Journal Article}, abstract = {

Understanding the conductivity variations induced by compositional changes in sodium super ionic conducting (NASICON) glass materials is highly relevant for applications such as solid electrolytes for sodium (Na) ion batteries. In the research reported in this paper, NASICON-based NCAP glass (Na2.8Ca0.1Al2P3O12) was selected as the parent glass. The present study demonstrates the changes in the Na+ ion conductivity of NCAP bulk glass with the substitution of boron (NCABP: Na2.8Ca0.1Al2B0.5P2.7O12) and gallium (NCAGP: Na2.8Ca0.1Al2Ga0.5P2.7O12) for phosphorus and the resulting structural variations found in the glass network. For a detailed structural analysis of NCAP, NCABP and NCAGP glasses, micro-Raman and magic angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopic techniques (for 31P, 27Al, 23Na, 11B and 71Ga nuclei) were used. The Raman spectrum revealed that the NCAP glass structure is more analogous to the AlPO4 mesoporous glass structure. The 31P MAS-NMR spectrum illustrated that the NCAP glass structure consists of a high concentration of Q0 (3Al) units, followed by Q0 (2Al) units. The 27Al MAS-NMR spectrum indicates that alumina exists at five different sites, which include AlO4 units surrounded by AlO6 units, Al(OP)4, Al(OP)5, Al(OAl)6 and Al(OP)6, in the NCAP glass structure. The 31P, 27Al and 11B MAS-NMR spectra of the NCABP glass revealed the absence of B{\textendash}O{\textendash}Al linkages and the presence of B3{\textendash}O{\textendash}B4{\textendash}O{\textendash}P4 linkages which further leads to the formation of borate and borophosphate domains. The 71Ga MAS-NMR spectrum suggests that gallium cations in the NCAGP glass compete with the alumina cations and occupy four (GaO4), five (GaO5) and six (GaO6) coordinated sites. The Raman spectrum of NCAGP glass indicates that sodium cations have also been substituted by gallium cations in the NCAP glass structure. From impedance analysis, the dc conductivity of the NCAP glass (\~{}3.13 {\texttimes} 10-8 S cm-1) is slightly decreased with the substitution of gallium (\~{}2.27 {\texttimes} 10-8 S cm-1) but considerably decreased with the substitution of boron (\~{}1.46 {\texttimes} 10-8 S cm-1). The variation in the conductivity values are described based on the structural changes of NCAP glass with the substitution of gallium and boron.

}, issn = {20462069}, doi = {10.1039/C8RA01676C}, author = {Allu, Amarnath R.}, editor = {Balaji, Sathravada} } @article {46236, title = {Raman and Na-23 solid-state NMR studies on the lead-free ferroelectrics Bi-0.5(Na1-xKx)(0.5)TiO3 in the morphotropic phase boundary region}, journal = {Materials Research Bulletin}, volume = {118}, year = {2019}, month = {OCT}, type = {Article}, abstract = {

The local structural changes, due to the substitution of the smaller Na+ by the larger K+ ion, in the lead-free piezoelectric ceramic compositions Bi-0.5(Na1-xKx)(0.5)TiO3 have been studied using Raman and Na-23 solid-state NMR spectroscopy. Different close compositions in the solid solution series Bi-0.5(Na1-xKx)(0.5)TiO3 (0 \<= x \<= 0.36, Delta x = 0.02) are studied in the morphotropic phase boundary (MPB) region arising from the different crystal structures of the end members Bi0.5Na0.5TiO3 and Bi0.5K0.5TiO3. Close correlations between the Raman and NMR parameters with the performance parameters of the system have been observed, suggesting the role of the local structural changes in determining these parameters. Raman and Na-23 NMR studies showed that the onset of the MPB region is at x = 0.16 and the MPB region corresponds to 0.16 \<= x \<= 0.24 where better performance parameters are observed.

}, doi = {10.1016/j.materresbull.2019.110506}, author = {Anjali, K. and Ajithkumar, T. G. and Joy, P. A.} } @article {46923, title = {Dynamics in amine-functionalized mesoporous hybrid materials probed through deuterium magic angle spinning NMR and molecular dynamic simulations}, journal = {Journal of Physical Chemistry C}, volume = {124}, year = {2020}, month = {MAR}, pages = {6154-6170}, type = {Article}, abstract = {

We present a deuterium magic angle spinning (MAS) NMR study on two widely used hybrid materials (3-glycidyloxy propyl)trimethoxysilane (3-GPTMS) and 3-(trimethoxysilyl)propyl methacrylate (3-MATMS) grafted on SBA-15. Methylene-deuterated diamine as a pendent group is anchored to GPTMS (O3Si-CH2-CH2-CH2-O-CH2-CH(OH)- CH2-NH-CD2-CD2-NH2) and MATMS (O3Si-CH2-CH2-CH2-O-C(N-CD2-CD2-NH2)-C(CH3)=-CH2) postgrafting. Proton and deuterium solid state NMR experiments under MAS were performed at two hydration levels and temperatures ranging from 253 to 315 K. Deuterium spectra were deconvoluted into three A Dr, components with different average quadrupolar parameters: a relatively rigid component arising from local or librational motion of C-H-2(2) corresponding to {\textquoteleft}{\textquoteleft}small angle{\textquoteright}{\textquoteright} jumps, an intermediate dynamic component, and a large amplitude dynamic component. Population ratios of rigid versus dynamic components show that diamine-MATMS is more rigid when compared with diamine-GPTMS at high hydration. The role of the length of the linkers, steric hindrance, grafting concentration, etc. in defining mobility is investigated. Finally, by correlating proton and deuterium MAS NMR spectral analysis, the role of a few water molecules in inducing dynamics of the linkers was investigated. Molecular dynamic (MD) simulations support the experimental analysis. MD simulations indicate different types of mobility arising from the same molecular binding configuration of diamine-MATMS. Dynamics induced by a few hydroxyls on the pore surface accessible to the linker, various molecular conformations, and stabilization of the linker through hydrogen bonding with the surface, derived from MD simulations, are discussed.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.9b11948}, author = {Veena, V. S. and Kavya, I and Lazar, A. and Vinod, C. P. and Ajithkumar, T. G. and Jayanthi, S.} } @article {46747, title = {Elucidating the effect of CaF 2 on structure, biocompatibility and antibacterial properties of S53P4 glass}, journal = {Journal of Alloys and Compounds}, volume = {831}, year = {2020}, month = {AUG }, pages = {154704}, type = {Article}, abstract = {

The present work focuses on the synthesis and structural elucidation of fluoride containing bioactive glasses in the system (in mol\%) given by (53.86) SiO2\ {\textendash} (22.65) Na2O {\textendash} (21.77-x) CaO {\textendash} (1.72) P2O5\ {\textendash} x CaF2, where, x\ =\ 0, 5.44, 10.885 and 16.33. The role of the incorporated fluoride and its distribution within the glass were interpreted and analyzed using Molecular dynamics (MD) simulations and the results were compared with the modified random network (MRN) model. The interpretations from the model have been verified using the MAS-NMR spectroscopy technique. According to this model, fluoride containing bioactive glasses have been proposed to consist of silicate rich network regions and modifier cation {\textendash} fluoride rich inter-network regions. The interface region was found to consist of non-bridging oxygen species (NBO) and phosphate cations which are either isolated orthophosphates (Q0P) or bridged with silicates in the form of pyrophosphate (Q1P) units forming Si{\textendash}O{\textendash}P bonds. The gradual substitution of CaF2\ for CaO in the base glass resulted in an increase in the silicate network connectivity with a reduction in the NBOs and lead to an increase in the association of modifier cations with fluoride ions. However, fluoride ions were found to show a marginal preference to associate with Na+\ cations leading to a decrease in the association of Na+\ ions with orthophosphate and silicate units. These overall structural findings were correlated with the\ in\ vitro\ ion dissolution behaviour of the bioactive glasses as well as with the thermal properties. The glasses were tested for their\ in\ vitro\ cell viability towards mouse osteoblast type (MC3T3) cells in which fluoride containing bioactive glasses did not show any toxicity and exhibited better cell proliferation. The antibacterial efficacy of the fluoride containing glasses was tested at various concentrations (5, 10 and 20\ mg/ml) in\ E.coli\ bacterial inoculum in which bactericidal action was evidenced.

}, keywords = {Fluoride bioactive glasses, In~vitro apatite formation and bactericidal action, MAS-NMR spectroscopy, MD simulations}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2020.154704}, author = {Prasad, Sakthi and Ganisetti, Sudheer and Jana, Anuradha and Kant, Shashi and Sinha, P. K. and Tripathy, Sucheta and Illath, Kavya and Ajithkumar, T. G. and Annapurna, K. and Allu, Amarnath R. and Biswas, Kaushik} } @article {46940, title = {FeNx/FeSx-anchored carbon sheet-carbon nanotube composite electrocatalysts for oxygen reduction}, journal = {ACS Applied Nano Materials}, volume = {3}, year = {2020}, month = {MAR}, pages = {2234-2245}, type = {Article}, abstract = {

Even though various Pt-free electrocatalysts for oxygen reduction reaction (ORR) have been introduced, many of them are found to be active only in alkaline conditions. Considering Nafion, phosphoric acid-doped polybenzimidazole (PBI), and so on as the prominent ionomer membranes, used in the commercially available polymer electrolyte membrane fuel cells (PEMFCs), it becomes important that any development on the Pt-free catalysts should ensure the better ORR performance under acidic conditions. The present work effectively tackles this issue, where an ORR-based catalyst could be prepared with simultaneous incorporation of both Fe-N and Fe-S active sites on in situ generated carbon sheets which are spatially separated by the carbon nanotube (CNT) network. This catalyst shows ability to perform under both acidic and basic conditions. This has been achieved by growing a polyethylenedioxythiophene polymer network in the presence of CNT and melamine followed by its pyrolysis under an inert atmosphere. The catalyst formed at 900 degrees C (PMCNT-900) displays 0.94 V onset potential for ORR under acidic electrolyte conditions, which corresponds to 60 mV overpotential compared to its 40 wt \% Pt/C counterpart. Interestingly, in single cell demonstration of Nafion-based PEMFC with PMCNT-900 as the cathode catalyst, the system delivered a maximum power density (PD) of 500 and 275 mW/cm(2) at 60 degrees C under H-2-O-2 and H-2-air feed conditions, respectively. On the other hand, in a single cell test in the anion exchange membrane fuel cell (AEMFC) mode, a maximum power density of 65 mW/cm(2) at 50 degrees C could be achieved with the same cathode catalyst, which is a comparable value obtained while employing Pt/C as the cathode. These results, thus, infer to the efficiency of the catalyst to facilitate ORR under the extreme pH conditions, and particularly its performance under acidic condition reveals its prospect as a potential Pt-free electrocatalyst to serve in the Nafion-based systems.

}, keywords = {carbon nanotube, electrocatalyst, fuel cell, oxygen reduction reaction, Pt-free ORR}, issn = {2574-0970}, doi = {10.1021/acsanm.9b02335}, author = {Bhange, Siddheshwar N. and Soni, Roby and Singla, Gourav and Ajithkumar, T. G. and Kurungot, Sreekumar} } @article {46702, title = {Photocatalytic hydrogen generation and CO2 conversion using g-C3N4 decorated dendritic fibrous nanosilica: role of interfaces between silica and g-C3N4}, journal = {ACS Applied Energy Materials}, volume = {3}, year = {2020}, month = {SEP }, pages = {8150-8158}, type = {Article}, abstract = {

We have synthesized g-C3N4 decorated over dendritic fibrous nanosilica (DFNS). The generation of C-N-Si interfaces by coating each fiber of DFNS with g-C3N4 not only provided high surface area but also affected the optical and electronic properties of the composite. The catalyst synthesis reproducibility issue of g-C3N4 was resolved using a vacuum-sealed quartz tube. The extended light absorption in the visible region, enhanced lifetime of photogenerated charge carriers due to the formation of interfaces between silica and g-C3N4 (confirmed by solid-state NMR), and increased surface area result in the improved photocatalytic activity of DFNS/g-C(3)N(4)for hydrogen generation and CO2 conversion.

}, keywords = {CO2 conversion, DFNS, g-C3N4, Hydrogen generation, nanocatalysts, photocatalysts, Solid-state NMR}, issn = {2574-0962}, doi = {10.1021/acsaem.0c01265}, author = {Rawool, Sushma A. and Samanta, Anupam and Ajithkumar, T. G. and Kar, Yusuf and Polshettiwar, Vivek} } @article {47736, title = {Elucidating the effect of CaF2 on structure, biocompatibility and antibacterial properties of S53P4 glass (vol 831, 154704, 2020)}, journal = {Journal of Alloys and Compounds}, volume = {883}, year = {2021}, month = {NOV}, pages = {161253}, type = {Correction}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2021.161253}, author = {Prasad, Sakthi and Ganisetti, Sudheer and Jana, Anuradha and Kant, Shashi and Sinha, P. K. and Tripathy, Sucheta and Illath, Kavya and Ajithkumar, T. G. and Annapurna, K. and Allu, Amarnath R. and Biswas, Kaushik} } @article {47031, title = {Synthesis and characterization of LAGP-glass-ceramics-based composite solid polymer electrolyte for solid-state Li-ion battery application}, journal = {Journal of Non-Crystalline Solids}, volume = {558}, year = {2021}, month = {APR }, pages = {120654}, type = {Article}, abstract = {

Solid State Electrolytes (SSEs) are the future alternatives of the present conventional liquid electrolytes in terms of safety, high temperature stability and also good electrochemical performance. Glass (G), based on Lithium Aluminium Germanium Phosphate (LAGP) was prepared and converted into glass-ceramics (GC) by optimized heating schedule. The crystalline LAGP has Na Super Ionic CONductor (NASICON) type unit cell where the lithium ions hop between two different positions providing long range ionic motion. To improve the inter electrode surface resistance and cell performance, Composite Solid Electrolyte (CSE) was prepared with poly (vinylidene fluoride-co-hexaflurophoaphate) (P(VDF-HFP)), 20wt\% LAGP, Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1-Ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI). X-ray diffraction patterns confirm the formation of the NASICON phase in LAGP GC and the amorphous nature of the CSE. NMR studies confirm formation of the Ge/AlO6 octahedra and PO4 tetrahedra inside the crystal. 7Li NMR also confirmed two different Lithium sites in LAGP crystal. The ionic conductivity values of CSE and LAGP GC are (4.49 +/- 0.31) x 10(-3)Scm(-1) and (2.70 +/- 0.04) x 10(-4)Scm(-1), respectively. The thermal stability of the prepared CSE is tested upto 315 degrees C without any degradation. Two cells (Cell-I \& Cell-II) were fabricated using the LAGP GC and CSE respectively. Cell-II shows the specific discharge capacity of 151mAhg1 at 50th cycle which is higher as compared to Cell-I (129mAhg(-1)) when tested at the C-rate of 0.05 degrees C.

}, keywords = {Lithium germanium phosphate, NASICON, Solid state electrolyte, Solid state NMR}, issn = {0022-3093}, doi = {10.1016/j.jnoncrysol.2021.120654}, author = {Das, Anurup and Goswami, Madhumita and Illath, Kavya and Ajithkumar, T. G. and Arya, A. and Krishnan, M.} } @article {48231, title = {Effect of oxalic acid and sulphuric acid hydrolysis on the preparation and properties of pineapple pomace derived cellulose nanofibers and nanopapers}, journal = {International Journal of Biological Macromolecules}, volume = {209}, year = {2022}, month = {JUN }, pages = {1745-1759}, type = {Article}, abstract = {

Nanocellulose is the {\textquoteleft}{\textquoteleft}green magnet{\textquoteright}{\textquoteright} which attracts a wide spectrum of industries towards it due to its availability, biodegradability, and possible smart applications. For the first time, pineapple pomace was being explored as an economic precursor for cellulose nanofibers. Nanofiber isolation was accomplished using a chemo-mechanical method and solution casting was adopted for the development of nanopapers. Moreover, the study examines the structural, optical, crystalline, dimensional, and thermal features of nanofibers isolated using different acid hydrolysis (oxalic acid and sulphuric acid) methods. Fourier-transform infra-red spectroscopy, 13C solid-state nuclear magnetic resonance spectroscopy, and X-ray diffraction analysis indicated the presence of type I cellulose. The transmittance, crystallinity index, and thermal stability of PPNFS (sulphuric acid treated fiber) were greater than PPNFO (oxalic acid treated fiber). The transmission electron microscopy and dynamic light scattering analysis confirmed the nanodimension of PPNFO and PPNFS. While comparing the optical and mechanical properties of nanopapers, PPNFS outperforms PPNFO. The tensile strength of the prepared nanopapers (64 MPa (PPNFO) and 68 MPa (PPNFS)) was found to be high compared to similar works reported in the literature. The prepared nanopaper is proposed to be used for food packaging applications.

}, keywords = {cellulose nanofibers, Cellulosic nanopapers, Pineapple pomace}, issn = {0141-8130}, doi = {10.1016/j.ijbiomac.2022.04.138}, author = {Neenu, K. V. and Dominic, C. D. Midhun and Begum, P. M. Sabura and Parameswaranpillai, Jyotishkumar and Kanoth, Bipinbal Parambath and David, Deepthi Anna and Sajadi, S. Mohammad and Dhanyasree, P. and Ajithkumar, T. G. and Badawi, Michael} } @article {47719, title = {The effects of cis and trans butenedioic acid on the physicochemical behavior of lumefantrine}, journal = {Crystengcomm}, volume = {24}, year = {2022}, month = {JAN }, pages = {156-168}, type = {Article}, abstract = {The present work investigates the effects of cis and trans butenedioic acid isomers (maleic acid and fumaric acid) on the crystallinity and pharmaceutical behavior of lumefantrine. Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), attenuated total reflectance infrared spectroscopy (ATR-IR), solid-state nuclear magnetic resonance spectroscopy (ss-NMR), and single-crystal X-ray diffraction (SC-XRD) studies were employed. Lumefantrine-fumaric acid crystallized as a salt in the monoclinic space group P2(1)/c. In comparison, DSC and PXRD showed the formation of a co-amorphous solid with maleic acid. Complete proton transfer with a strong ionic interaction led to crystalline salt formation with the trans isomer, whereas weaker/fewer hydrogen bonds with the cis isomer of butenedioic acid led to a co-amorphous salt. The in vitro dissolution of both salts resulted in a similar 2.6-2.7-fold improvement in dissolution rate when compared to that of the crystalline lumefantrine. The crystalline and co-amorphous salts were stable under accelerated stability conditions (40 +/- 2 degrees C and 75 +/- 5\% RH) for one month.}, doi = {10.1039/d0ce01709d}, author = {Tomar, Devendrasingh and Lodagekar, Anurag and Gunnam, Anilkumar and Allu, Suryanarayana and Chavan, Rahul B. and Tharkar, Minakshi and Ajithkumar, T. G. and Nangia, Ashwini K. and Shastri, Nalini R.} } @article {48471, title = {Investigation of Al2O3 induced variations in the structural parameters in strontium borosilicate glasses using solid state NMR}, journal = {Physical Chemistry Chemical Physics}, volume = {25}, year = {2023}, month = {MAY }, pages = {13550-13559}, type = {Article}, abstract = {

The physical properties of oxide glasses are crucially dependent on the atomistic structural speciation. In this study, we investigate the variation in the local ordering in the glass network of strontium borosilicate glasses (34.82 SrO, 51.84 B2O3, 13.34 SiO2 in mol\%) with a progressive substitution of B2O3 by Al2O3 and estimate the structural parameters: the oxygen packing fraction, and the average network coordination number. The coordination of the network forming cations at various glass compositions is determined using B-11, Al-27, and Si-29 solid-state nuclear magnetic resonance (SSNMR). The SSNMR reveals that at the higher substitution of B2O3 by Al2O3 in the glass composition, the coordination network of Al3+ exists predominantly in the 4 coordinated state, the network forming B3+ cations transform from a tetrahedral BO4 to a trigonal BO3 structure, and the Q(4) form of silicates is dominant. The average coordination number and the oxygen packing fraction were calculated using the parameters obtained from the SSNMR results, and it is observed that the average coordination number decreases, and the oxygen packing fraction increases on incorporating Al. It is interesting to note that some of the thermophysical properties of these compositions closely follow the pattern shown by the average coordination number and the oxygen packing fraction.

}, issn = {1463-9076}, doi = {10.1039/d3cp00751k}, author = {Illath, Kavya and Ojha, Prasanta K. and Rath, Sangram K. and Ajithkumar, T. G.} } @article {48834, title = {Nanosilica from Averrhoa bilimbi juice pre-treated rice husk: preparation and characterization}, journal = {Journal of Cleaner Production}, volume = {413}, year = {2023}, month = {AUG }, pages = {137476}, type = {Article}, abstract = {

The preparation of nanosilica from rice husk without using any concentrated mineral acids is a novel concept. This work proposes a bioleaching strategy to remove metallic impurities from rice husk for the preparation of nanosilica. Herein, nanosilica (BJRHS) was prepared by calcinating Averrhoa bilimbi juice pre-treated rice husks in a muffle furnace. The chemical and atomic structures of commercial precipitated silica (CS), rice husk ash (RHA), and BJRHS were analyzed using different analytical techniques. The optimal leaching time, calcination temperature, and calcination time were 1 h, 500 degrees C, and 6 h respectively. The particle size of BJRHS was found to be 6-12 nm, which is less than that of RHA and CS. The BET surface area of BJRHS (204 m2/g) was found to be greater than RHA (110.5 m2/g) and CS (172.1 m2/g). Mesoporous nanosilica with excellent surface area and purity was produced sustainably from rice husk which could be recommended to use in the field of catalysis, polymer technology, etc.

}, keywords = {Averrhoa bilimbi juice, Bioleaching, Nanosilica, rice husk}, issn = {0959-6526}, doi = {10.1016/j.jclepro.2023.137476}, author = {Dominic, C. D. Midhun and Neenu, K. V. and Begum, P. M. Sabura and Joseph, Rani and Rosa, Derval dos Santos and Duan, Yongxin and Balan, Aiswarya and Ajithkumar, T. G. and Soumya, Mary and Shelke, Ankita and Parameswaranpillai, Jyotishkumar and Badawi, Michael} } @article {49064, title = {Extraction, characterization, and life cycle assessment of nanosilica from millet husk: sustainable alternative with low environmental impact}, journal = {Journal of Cleaner Production }, volume = {442}, year = {2024}, month = {FEB}, pages = {140924}, type = {Article}, abstract = {

Eco-friendly approaches for silica production are highly researched to respond increasing industrial demand for bio-nanofillers. Herein, nanosilica of 10-20 nm with mesoporosity was obtained through a mild oxalic acid pre-treatment of millet husk, followed by calcination at 700 degrees C for 2 h. Compared with commercial precipitated silica (CS) and millet husk ash (MHA) directly obtained by calcination of the husk, the pre-treated silica (MHS) had higher purity, revealed using EDX spectroscopy. Moreover, FTIR and Si-29 NMR showed a higher condensation degree in MHS with 73\% of Q4 siloxane bonds vs 4\% in MHA. The release of the metal and organic impurities from the husk also allows to reduce the crystallinity of MHS, and to increase the specific surface area from 82 m(2)/g in MHA to 238 m(2)/g in MHS. The type II N-2 adsorption-desorption isotherms of MHA and MHS indicate aggregates of non-porous silica particles. MHS also demonstrated remarkable thermal resilience. According to the LCA analysis, MHS has a 40\% lower impact on global warming, a 38\% lower impact on human carcinogenic toxicity, and a 38\% lower impact on terrestrial acidification compared to rice husk nanosilica. This research thus addresses sustainability challenges by repurposing millet husks, which are readily available due to continuous millet cultivation, particularly in India. By reducing the ecological impact of husk disposal through burning, this study offers an economically viable technology for high-purity silica production, aligning with global efforts to combat climate change and promote sustainable practices.

}, keywords = {Life cycle assessment, Millet husk, Nanosilica, Oxalic acid}, issn = {0959-6526}, doi = {10.1016/j.jclepro.2024.140924}, author = {Dominic, C. D. Midhun and Rosa, Derval dos Santos and Barbosa, Rennan Felix da Silva and Anagha, O. V. and Neenu, K. V. and Begum, P. M. Sabura and Kumar, V. Aswathy and Parameswaranpillai, Jyotishkumar and Siriwong, Chomsri and Ajithkumar, T. G. and Shelke, Ankita and Pasc, Andreea} } @article {49457, title = {Green engineering of cellulose nanofibers and nanopapers from Wodyetia bifurcata fruits: a sustainable approach with emphasis on process optimization and tensile property assessment}, journal = {Biomass Conversion and Biorefinery}, year = {2024}, month = {MAY}, type = {Article}, abstract = {

Nanocellulose emerges as a highly promising material with versatile applications, offering solutions to environmental and sustainability challenges. This study delves into the extraction of cellulose nanofibers (CNFs) from\ Wodyetia bifurcata\ fruit pulp through mild oxalic acid hydrolysis assisted by steam explosion. To ensure environmental compatibility, chlorine-free pre-treatments were applied to eliminate non-cellulosic components. Chemical composition analysis verified the effective removal of non-cellulosic elements, validated by Fourier transform infrared spectroscopy (FTIR). Solid-state\ 13C nuclear magnetic resonance (13C NMR) spectroscopy confirmed the presence of type I cellulose α-polymorph in the CNF, while a crystallinity index of 60\% was determined by X-ray diffraction analysis (XRD). The transmission electron microscopy (TEM)\ images revealed a fibrous morphology with a fiber diameter ranging from 9 to 36\ nm. Dynamic light scattering (DLS) was employed to corroborate the observed fiber diameter. Mild acid hydrolysis elevated the maximum degradation temperature (Tmax) of CNF to 39\ {\textdegree}C compared to the pristine sample. Furthermore, this research explores the application of CNFs in nanopaper development using a casting method. The resulting nanopapers exhibited a tensile strength of ~ 17\ MPa and a transmittance of 25\%. These nanopapers present a viable pathway toward eco-friendly products in various industries, promising to revolutionize upcoming sustainable packaging technologies.

}, doi = {10.1007/s13399-024-05751-7}, author = {Sankar, Sameera and Neenu, K. V. and Parameswaranpillai, Jyotishkumar and Ajithkumar, T. G. and Shelke, Ankita Ramesh and Begum, P. M. Sabura and Bipinbal, P. K. and George, Tresa Sunitha and Badawi, Michael and Dominic, Midhun} } @article {49106, title = {In situ monitoring of competitive coformer exchange reaction by 1H MAS solid-state NMR}, journal = {Molecualr Pharmaceutics}, volume = {21}, year = {2024}, month = {FEB }, pages = {1479-1489}, type = {Article}, abstract = {

In a competitive coformer exchange reaction, a recent topic of interest in pharmaceutical research, the coformer in a pharmaceutical cocrystal is exchanged with another coformer that is expected to form a cocrystal that is more stable. There will be a competition between coformers to form the most stable product through the formation of hydrogen bonds. This will cause destabilization of the pharmaceutical products during processing or storage. Therefore, it is important to develop a mechanistic understanding of this transformation by monitoring each and every step of the reaction, employing a technique such as H-1 nuclear magnetic resonance (NMR). In this study, an in situ monitoring of a coformer exchange reaction is carried out by H-1 magic angle spinning (MAS) solid-state NMR (SSNMR) at a spinning frequency of 60 kHz. The changes in caffeine maleic acid cocrystals on addition of glutaric acid and caffeine glutaric cocrystals on addition of maleic acid were monitored. In all of the reactions, it has been observed that caffeine glutaric acid Form I is formed. When glutaric acid was added to 2:1 caffeine maleic acid, the formation of metastable 1:1 caffeine glutaric acid Form I was observed at the start of the experiment, indicating that the centrifugal pressure is enough for the formation. The difference in the end product of the reactions with a similar reaction pathway of 1:1 and 2:1 reactant stoichiometry indicates that a complete replacement of maleic acid has occurred only in the 1:1 stoichiometry of the reactants. The polymorphic transition of caffeine glutaric acid Form II to Form I at higher temperatures was a crucial reason that triggered the exchange of glutaric acid with maleic acid in the reaction of caffeine glutaric acid and maleic acid. Our results are novel since the new reaction pathways in competitive coformer exchange reactions enabled understanding the remarkable role of stoichiometry, polymorphism, temperature, and centrifugal pressure.

}, keywords = {caffeine cocrystal, coformer exchange reaction, in situ monitoring, polymorphism, Solid-state NMR}, issn = {1543-8384}, doi = {10.1021/acs.molpharmaceut.3c01118}, author = {Hareendran, Chaithanya and Alsirawan, Bashir and Paradkar, Anant and Ajithkumar, T. G.} } @article {49041, title = {Insights into the structure of sucralfate by advanced solid- and liquid-state NMR}, journal = {Molecualr Pharmaceutics }, volume = {21}, year = {2024}, month = {FEB }, pages = {1390-1401}, type = {Article}, abstract = {

Sucralfate, which is a sucrose octasulfate aluminum complex, is an active pharmaceutical ingredient (API) falling in the category of cytoprotective agents which are very effective for gastric and duodenal ulcers. On interaction with stomach acid, it ionizes into aluminum and sucrose octasulfate ions to form a protective layer over the ulcerated region inhibiting further attack from acid. The mechanism of action of sucralfate in the context of its structure is not well understood. Considering that at least two forms of this API are available in the market, there are no reports on the various forms of sucralfate and differences in their pharmacological action. We characterized the two forms of sucralfate using multinuclear, multidimensional solid-state NMR, and the results show significant structural differences between them arising from variation in the aluminum environment and the level of hydration. The impact of structural differences on pharmacological action was examined by studying acid-induced Al release by Al-27 liquid-state NMR. The sucralfate, European pharmaceutical standard, Form I, undergoes faster disruption in acid compared to Form II. The difference is explained on the basis of structural differences in the two forms which gives significant insights into the action of sucralfate in relation to its structure.

}, keywords = {(27)AlMQMAS, H-1-H-1 DQSQ, pharmacological action, solid-stateNMR, sucralfate}, issn = {1543-8384}, doi = {10.1021/acs.molpharmaceut.3c01042}, author = {Hareendran, Chaithanya and Ravindranathan, Sapna and Ajithkumar, T. G.} } @article {49042, title = {Solid-state NMR method for characterization of pharmaceutical eutectics}, journal = {Physical Chemistry Chemical Physics}, volume = {26}, year = {2024}, month = {JAN }, pages = {3800-3803}, type = {Article}, abstract = {

Pharmaceutical eutectics are extremely useful for designing formulations, and currently, there are no techniques other than differential scanning calorimetry (DSC) that can confirm their formation. In this study, we demonstrate that 1H fast magic angle spinning (MAS) solid-state NMR (SSNMR) experiments can confirm the formation of eutectics by detecting their intermolecular hydrogen bonding interactions. 2D 1H-1H double quantum single quantum (DQSQ) correlation SSNMR experiment is demonstrated which can confirm the formation of pharmaceutical eutectics for which there are no techniques other than differential scanning calorimetry (DSC).

}, issn = {1463-9076}, doi = {10.1039/d3cp05615e}, author = {Hareendran, Chaithanya and Shaligram, Parth S. and Gonnade, Rajesh and Ajithkumar, T. G.} } @article {49460, title = {Valorization of avocado peel waste: extraction and characterization of cellulose nanofibers for multifunctional applications}, journal = { Biomass Conversion and Biorefinery}, year = {2024}, month = {SEP}, type = {Article}, abstract = {

This study explored the utility of underutilized avocado peels for extracting cellulose nanofibers (CNFs). Mild oxalic acid hydrolysis assisted by steam explosion was employed after alkali hydrolysis and chlorine-free bleaching to prepare cellulose nanofibers. The structural, atomic, and elemental features of the extracted fibers were studied using Fourier transform infrared spectroscopy (FTIR),\ 13C solid-state nuclear magnetic resonance (13C NMR) spectroscopy, and energy dispersive X-ray (EDAX) analysis, respectively. The crystallinity index of the nanofibers was 87\%, which was 53\% greater than that of the crude sample. The elution of hemicellulose and lignin was evident from the scanning electron microscopy (SEM) images, and the nanofibers had a fiber diameter of 30{\textendash}82\ nm according to the transmission electron microscopy (TEM) analysis. The applied chemical treatment also elevated the thermal stability of the fibers. The extracted fibers can be applied in numerous fields, including electronics, packaging, automobiles, biomedicine, and cosmetics.

}, doi = {https://doi.org/10.1007/s13399-024-06065-4}, author = {Varsha, P. V. and Neenu, K. V. and Begum, P. M. Sabura and Hounfodji, Jean Wilfried and Sankar, Sameera and Muraleedharan, Sneha and Kamath, Anjali N. and Ajithkumar, T. G. and Parameswaranpillai, Jyotishkumar and Midhun, Dominic C. D.} }