72 results on '"Ravichandar R"'
Search Results
2. Morpheus: Semantics-based Incremental Change Propagation in SOA-based Solutions.
- Author
-
Ravichandar, R., Narendra, N.C., Ponnalagu, K., and Gangopadhyay, D.
- Published
- 2008
- Full Text
- View/download PDF
3. Coordination Environment and Distance Optimization of Dual Single Atoms on Fluorine-Doped Carbon Nanotubes for Chlorine Evolution Reaction.
- Author
-
Shao X, Maibam A, Cao F, Jin H, Huang S, Liang M, Gyu Kim M, My Tran K, Jadhav AR, Seung Jung H, Babarao R, and Lee H
- Abstract
The chlorine evolution reaction (CER) is a crucial anode reaction in the chlor-alkali industrial process. Precious metal-based dimensionally stable anodes (DSA) are commonly used as catalysts for CER but are constrained by their high cost and low selectivity. Herein, a Pt dual singe-atom catalyst (DSAC) dispersed on fluorine-doped carbon nanotubes (F-CNTs) is designed for an efficient and robust CER process. The prepared Pt DSAC demonstrates excellent CER activity with a low overpotential of 21 mV to achieve a current density of 10 mA cm
-2 and a remarkable mass activity of 3802.6 A gpt -1 at an overpotential around 30 mV, outperforming those of commercial DSA and Pt single-atom catalyst. The excellent CER performance of Pt DSAC is attributed to the high atomic utilization and improved intrinsic activity. Notably, introducing fluorine atoms on CNTs increases the oxidation and chlorination resistance of Pt DSAC, and reduces the demetalization ratio of Pt atoms, resulting in excellent long-term CER stability. Theoretical calculations reveal that several Pt DSAC configurations with optimized first-shell ligands and interatomic distance display lower energy barriers for Cl intermediates generation and weaker ionic Pt-Cl bond interaction, which are favorable for the CER process., (© 2024 Wiley-VCH GmbH.)- Published
- 2024
- Full Text
- View/download PDF
4. Revving Up a Designed Copper Catecholate Porous Organic Polymer for Its Potent Ethylene Adsorption than Ethane.
- Author
-
Das N, Maibam A, Yun H, Boro B, Hong CS, Babarao R, and Mondal J
- Abstract
The potential to produce high-purity C
2 H4 has made ethylene-selective adsorbents for ethane (C2 H6 )/ethylene (C2 H4 ) gas mixture separation appealing as viable substitutes for traditional cryogenic distillation. In this aspect, porous organic polymers (POPs) are anticipated to become the next-generation potential adsorbent due to their easily customizable functions and functional sites suitable for gas separation. This article reports the selective C2 H4 adsorption over C2 H6 using microporous copper(I)-coordinated POP ( Cu@Di-POP ) via fine-tuning of the π complexation and pore size. The specially designed adsorbent has the ideal pore size and coordinated Cu(I) ions to form π-complexation with C2 H4 molecules, which enabled it to adsorb C2 H4 (at 1 bar, 24.9, 18.9, and 13.4 cm3 g-1 at 273, 298, and 323 K, respectively) while significantly reducing C2 H6 adsorption (at 1 bar, 16.9, 12.7, and 8.8 cm3 g-1 at 273, 298, and 323 K, respectively). At 1 bar, Cu@Di-POP exhibited IAST selectivities of 6.09, 5.60, and 4.13 for C2 H4 /C2 H6 at 273, 298, and 323 K, respectively, suggesting its C2 H4 selective behavior, which was further confirmed from the experimental breakthrough measurement. Furthermore, the computational studies carried out with density functional theory highlighted an enhanced charge distribution leading to dπ-pπ conjugation between C2 H4 π-electrons and Cu d-electrons, thereby showing a relatively higher interaction energy of -37.23 kcal/mol with C2 H4 as compared to -16.06 kcal/mol with C2 H6 gas molecules.- Published
- 2024
- Full Text
- View/download PDF
5. Clemastine Induces Oligodendrocyte Progenitor Pool Exhaustion and Senescence in the Context of Chronic Demyelination in a Rabbit Model.
- Author
-
Cooper JJM, Muthaiah R, Frost JR, Buck GT, Ravichandar R, Gadelkarim F, Raymond FD, and Sim FJ
- Abstract
Objectives: Clemastine has emerged as a promising therapy for the restoration of neurologic function in patients with multiple sclerosis (MS). However, clemastine and other agents with prodifferentiative effects on oligodendrocyte progenitor cells (OPCs) in rodent models have underperformed in clinical trials. We hypothesized that the preclinical studies showed more robust effects because of the abundance of OPCs in rodent models. To better examine the therapeutic potential of clemastine, we examined its effect on demyelinated white matter lesions in rabbits, which exhibit progenitor densities and limited remyelination more closely matching those found in tissues from patients with MS., Methods: We used lysolecithin to induce demyelination in white matter of New Zealand rabbits and then administered oral clemastine (10mg/kg/day) for various periods before assessing the OPC and oligodendrocyte (OL) populations in these lesions., Results: Daily administration of clemastine for the full study period (56 days) increased oligodendrogenesis in white matter lesions. However, shorter durations of treatment failed to increase overall OL density despite enhancing OPC-to-OL differentiation. This effect was due to exhaustion of the OPC pool, as the differentiating progenitors were not replaced because of reduced OPC proliferation. Notably, delayed administration of clemastine led to an accumulation of activated OPCs expressing markers of senescence., Interpretation: Although capable of driving OL differentiation, clemastine treatment in rabbits hampered progenitor pool replenishment, induced senescence, and promoted conversion of microglia/macrophages to a proinflammatory phenotype. Whether these effects would also occur in humans or with other prodifferentiative therapies should be studied further, but our data suggest the need to carefully consider progenitor dynamics in the treatment of MS. ANN NEUROL 2024., (© 2024 American Neurological Association.)
- Published
- 2024
- Full Text
- View/download PDF
6. Topological control in paddlewheel metal-organic cages via ligand length variation.
- Author
-
Tsoukatos S, Maibam A, Babarao R, and Bloch WM
- Abstract
Varying the length of phenanthrene-derived ligands switches the selective assembly of MIInL
n metal-organic cages (MOCs, n = 6 or 8) between tetrahedral, square, or triangular architectures. The limit of this approach is explored for both Cu2 and Rh2 paddlewheel MOCs, and supported by solution, solid-state and computational analysis.- Published
- 2024
- Full Text
- View/download PDF
7. Molecular docking analysis of imeglimin and its derivatives with estrogen receptor-alpha.
- Author
-
Elango A, Kannan I, Ravichandar R, and Kumaravelu P
- Abstract
Estrogen receptor-α (ER- α) is a principal endocrine regulatory protein in breast cancer. The progression of ER-α positive breast cancer is slowed by selective estrogen receptor modulators such as Tamoxifen. But, long term therapy with Tamoxifen leads to resistance. Therefore, it is of interest to document the Molecular docking and pharmacokinetic analysis of imeglimin derivatives with ER-alpha. Among the 166 derivatives of Imeglimin, only five derivatives were shortlisted after toxicity testing. The selected derivatives showed good binding affinity with favorable pharmacokinetic profiles. The selected compounds of Imeglimin were found to possess excellent anticancer potential and could be considered as novel, cost-effective anticancer agents effective against ER positive breast cancer for further investigation., (© 2024 Biomedical Informatics.)
- Published
- 2024
- Full Text
- View/download PDF
8. Dysregulated Cholinergic Signaling Inhibits Oligodendrocyte Maturation Following Demyelination.
- Author
-
Ravichandar R, Gadelkarim F, Muthaiah R, Glynos N, Murlanova K, Rai NK, Saraswat D, Polanco JJ, Dutta R, Pal D, and Sim FJ
- Subjects
- Animals, Mice, Female, Male, Mice, Inbred C57BL, Acetylcholine metabolism, Cuprizone toxicity, Lysophosphatidylcholines toxicity, Cell Differentiation drug effects, Cell Differentiation physiology, Choline O-Acetyltransferase metabolism, Remyelination physiology, Remyelination drug effects, Myelin Sheath metabolism, Myelin Sheath drug effects, Mice, Transgenic, Demyelinating Diseases metabolism, Demyelinating Diseases chemically induced, Demyelinating Diseases pathology, Oligodendroglia metabolism, Oligodendroglia drug effects, Signal Transduction drug effects, Signal Transduction physiology
- Abstract
Dysregulation of oligodendrocyte progenitor cell (OPC) recruitment and oligodendrocyte differentiation contribute to failure of remyelination in human demyelinating diseases such as multiple sclerosis (MS). Deletion of muscarinic receptor enhances OPC differentiation and remyelination. However, the role of ligand-dependent signaling versus constitutive receptor activation is unknown. We hypothesized that dysregulated acetylcholine (ACh) release upon demyelination contributes to ligand-mediated activation hindering myelin repair. Following chronic cuprizone (CPZ)-induced demyelination (male and female mice), we observed a 2.5-fold increase in ACh concentration. This increase in ACh concentration could be attributed to increased ACh synthesis or decreased acetylcholinesterase-/butyrylcholinesterase (BChE)-mediated degradation. Using choline acetyltransferase (ChAT) reporter mice, we identified increased ChAT-GFP expression following both lysolecithin and CPZ demyelination. ChAT-GFP expression was upregulated in a subset of injured and uninjured axons following intraspinal lysolecithin-induced demyelination. In CPZ-demyelinated corpus callosum, ChAT-GFP was observed in Gfap
+ astrocytes and axons indicating the potential for neuronal and astrocytic ACh release. BChE expression was significantly decreased in the corpus callosum following CPZ demyelination. This decrease was due to the loss of myelinating oligodendrocytes which were the primary source of BChE. To determine the role of ligand-mediated muscarinic signaling following lysolecithin injection, we administered neostigmine, a cholinesterase inhibitor, to artificially raise ACh. We identified a dose-dependent decrease in mature oligodendrocyte density with no effect on OPC recruitment. Together, these results support a functional role of ligand-mediated activation of muscarinic receptors following demyelination and suggest that dysregulation of ACh homeostasis directly contributes to failure of remyelination in MS., Competing Interests: The authors declare no competing financial interests., (Copyright © 2024 the authors.)- Published
- 2024
- Full Text
- View/download PDF
9. A Heterogeneous Acid-Base Organocatalyst For Cascade Deacetalisation-Knoevenagel Condensations.
- Author
-
Chhetri A, Maibam A, Maniam S, Babarao R, Wilson K, Lee AF, and Mitra J
- Abstract
Multifunctional heterogeneous catalysts are an effective strategy to drive chemical cascades, with attendant time, resource and cost efficiencies by eliminating unit operations arising in normal multistep processes. Despite advances in the design of such catalysts, the fabrication of proximate, chemically antagonistic active sites remains a challenge for inorganic materials science. Hydrogen-bonded organocatalysts offer new opportunities for the molecular level design of multifunctional structures capable of stabilising antagonistic active sites. We report the catalytic application of a charge-assisted, hydrogen-bonded crystalline material, bis(melaminium)adipate (BMA), synthesised from melamine and adipic acid, which possesses proximate acid-base sites. BMA exhibits high activity for the cascade deacetalisation-Knoevenagel condensation of dimethyl acetals to form benzylidenemalononitriles under mild conditions in water; BMA is amenable to large-scale manufacture and recycling with minimal deactivation. Computational modelling of the melaminium cation in protonated BMA explains the observed catalytic reactivity, and identifies the first demethoxylation step as rate-limiting, in good agreement with time-dependent 1H NMR and kinetic experiments. A broad substrate scope for the cascade transformation of aromatic dimethyl acetals is demonstrated., (© 2024 Wiley‐VCH GmbH.)
- Published
- 2024
- Full Text
- View/download PDF
10. Metal-Organic Frameworks for Enhanced Hydrogen Generation from Syngas: A Density Functional Theory Approach.
- Author
-
Gopalsamy K, Singh CP, Krishnamurty S, and Babarao R
- Abstract
Although methane poses environmental concerns, it is employed in hydrogen production processes such as steam-methane reforming (SMR), which has an issue of by-products released. Initiatives are being pursued to address CO and CO
2 emissions using carbon capture methods, with the goal of minimizing environmental harm while improving pure hydrogen generation from syngas. In this study, porous coordination network (PCN-250) has been studied for its selective adsorption property towards CO, CO2 and H2 O as syngas mixture to obtain pure hydrogen. For this purpose, the trimetallic cluster node Fe2 M (where Fe2 represents the 3+ oxidation state and M is Cr(II), Mn(II), Fe(II), Co(II), Ni(II), and Zn(II)) has been considered. Fe(III) in combination with metal atoms like Cr(II), Co(II), or Ni(II) has been found to exhibit enhanced adsorption properties towards CO, CO2 and H2 O. The molecule with the strongest interaction was found to be H2 O over Fe(III)2 Zn(II) cluster and weakest interaction was found between H2 and Fe(III)2 Ni(II). Charge transfer, natural bond orbital (NBO) and spin density analyses reveal the electronic structural properties of this combination, leading to enhanced adsorption of CO and CO2 ., (© 2024 The Authors. ChemPlusChem published by Wiley-VCH GmbH.)- Published
- 2024
- Full Text
- View/download PDF
11. Bimetallic Copper-Cerium-Based Metal-Organic Frameworks for Selective Carbon Dioxide Capture.
- Author
-
Jampaiah D, Shah D, Chalkidis A, Saini P, Babarao R, Arandiyan H, and Bhargava SK
- Abstract
Metal-organic frameworks (MOFs) are highly regarded as valuable adsorbent materials in materials science, particularly in the field of CO
2 capture. While numerous single-metal-based MOFs have demonstrated exceptional CO2 adsorption capabilities, recent advancements have explored the potential of bimetallic MOFs for enhanced performance. In this study, a CuCe-BTC MOF was synthesized through a straightforward hydrothermal method, and its improved properties, such as high surface area, smaller pore size, and larger pore volume, were compared with those of the bare Ce-BTC. The impact of the Cu/Ce ratio (1:4, 1:2, 1:1, and 3:2) was systematically investigated to understand how adding a second metal influences the CO2 adsorption performance of the Ce-BTC MOF. Various characterization techniques, including scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and N2 BET surface area analysis, were employed to assess the physical and chemical properties of the bare Ce-BTC and CuCe-BTC samples. Notably, CuCe-BTC-1:2 exhibited superior surface area (133 m2 g-1 ), small pore size (3.3 nm), and large pore volume (0.14 cm3 g-1 ) compared to the monometallic Ce-BTC. Furthermore, CuCe-BTC-1:2 demonstrated a superior CO2 adsorption capacity (0.74 mmol g-1 ), long-term stability, and good CO2 /N2 selectivity. This research provides valuable insights into the design of metal-BTC frameworks and elucidates how introducing a second metal enhances the properties of the monometallic Ce-BTC-MOF, leading to improved CO2 capture performance.- Published
- 2024
- Full Text
- View/download PDF
12. Purification of Waste-Generated Biogas Mixtures Using Covalent Organic Framework's High CO 2 Selectivity.
- Author
-
Paul R, Maibam A, Chatterjee R, Wang W, Mukherjee T, Das N, Yellappa M, Banerjee T, Bhaumik A, Venkata Mohan S, Babarao R, and Mondal J
- Abstract
Development of crystalline porous materials for selective CO
2 adsorption and storage is in high demand to boost the carbon capture and storage (CCS) technology. In this regard, we have developed a β-keto enamine-based covalent organic framework ( VM-COF ) via the Schiff base polycondensation technique. The as-synthesized VM-COF exhibited excellent thermal and chemical stability along with a very high surface area (1258 m2 g-1 ) and a high CO2 adsorption capacity (3.58 mmol g-1 ) at room temperature (298 K). The CO2 /CH4 and CO2 /H2 selectivities by the IAST method were calculated to be 10.9 and 881.7, respectively, which were further experimentally supported by breakthrough analysis. Moreover, theoretical investigations revealed that the carbonyl-rich sites in a polymeric backbone have higher CO2 binding affinity along with very high binding energy (-39.44 KJ mol-1 ) compared to other aromatic carbon-rich sites. Intrigued by the best CO2 adsorption capacity and high CO2 selectivity, we have utilized the VM-COF for biogas purification produced by the biofermentation of municipal waste. Compared with the commercially available activated carbon, VM-COF exhibited much better purification ability. This opens up a new opportunity for the creation of functionalized nanoporous materials for the large-scale purification of waste-generated biogases to address the challenges associated with energy and the environment.- Published
- 2024
- Full Text
- View/download PDF
13. Surface Electronic Properties-Driven Electrocatalytic Nitrogen Reduction on Metal-Conjugated Porphyrin 2D-MOFs.
- Author
-
Maibam A, Orhan IB, Krishnamurty S, Russo SP, and Babarao R
- Abstract
Two-dimensional (2D) metal organic framework (MOF) or metalloporphyrin nanosheets with a stable metal-N
4 complex unit present the metal as a single-atom catalyst dispersed in the 2D porphyrin framework. First-principles calculations on the 3d-transition metals in M-TCPP are investigated in this study for their surface-dependent electronic properties including work function and d-band center. Crystal orbital Hamiltonian population (-pCOHP) analysis highlights a higher contribution of the bonding state in the M-N bond and antibonding state in the N-N bond to be essential for N-N bond activation. A linear relationship between Δ Gmax and surface electronic properties, N-N bond strength, and Bader charge has been found to influence the rate-determining potential for nitrogen reduction reaction (NRR) in M-TCPP MOFs. 2D Ti-TCPP MOF, with a kinetic energy barrier of 1.43 eV in the final protonation step of enzymatic NRR, shows exclusive NRR selectivity over competing hydrogen reduction (HER) and nitrogenous compounds (NO and NO2 ). Thus, Ti-TCPP MOF with an NRR limiting potential of -0.35 V in water solvent is proposed as an attractive candidate for electrocatalytic NRR.- Published
- 2024
- Full Text
- View/download PDF
14. Robust Zeolitic Tetrazole Framework for Electrocatalytic Dopamine Detection with High Selectivity.
- Author
-
Sarfudeen S, Sruthi VP, Maibam A, Panda P, Jhariat P, Senthilkumar S, Babarao R, and Panda T
- Abstract
A novel zeolitic tetrazolate framework (ZTF-8) has been synthesized by solvent-free heat-assisted (70 °C) mechanochemical grinding of zinc acetate and 5-methyl tetrazole in the presence of NaOH powder. The structure of ZTF-8 adopts the zeolitic sodalite (SOD) topology with uncoordinated N-heteroatom sites and resembles the structure of the well-known zeolitic imidazole framework ZIF-8. ZTF-8 is exceptionally stable in 0.1 M aqueous acid and base solutions for 60 days at 25 °C. The unique structure with uncoordinated N-heteroatom active sites and exceptional stability of ZTF-8 facilitated the electrocatalytic oxidation of dopamine to dopamine quinone at neutral pH. Without any postsynthetic modification, ZTF-8 is directly used for the facile electrochemical detection of dopamine over a wide range of concentrations (5-550 μM) with a high sensitivity (2410.8 μA mM
-1 cm-2 ). It also demonstrated promising selectivity over other interferents of similar oxidation potential, such as ascorbic acid and uric acid. The DFT study revealed that the ZTF-8 framework has a higher binding energy (-145.07 kJ/mol) and stronger interaction with dopamine than its isostructural ZIF-8 structure (-130.42 kJ/mol).- Published
- 2023
- Full Text
- View/download PDF
15. Accelerating the prediction of CO 2 capture at low partial pressures in metal-organic frameworks using new machine learning descriptors.
- Author
-
Orhan IB, Le TC, Babarao R, and Thornton AW
- Abstract
Metal-Organic frameworks (MOFs) have been considered for various gas storage and separation applications. Theoretically, there are an infinite number of MOFs that can be created; however, a finite amount of resources are available to evaluate each one. Computational methods can be adapted to expedite the process of evaluation. In the context of CO
2 capture, this paper investigates the method of screening MOFs using machine learning trained on molecular simulation data. New descriptors are introduced to aid this process. Using all descriptors, it is shown that machine learning can predict the CO2 adsorption, with an R2 of above 0.9. The introduced Effective Point Charge (EPoCh) descriptors, which assign values to frameworks' partial charges based on the expected CO2 uptake of an equivalent point charge in isolation, are shown to be the second most important group of descriptors, behind the Henry coefficient. Furthermore, the EPoCh descriptors are hundreds of thousands of times faster to obtain compared with the Henry coefficient, and they achieve similar results when identifying top candidates for CO2 capture using pseudo-classification predictions., (© 2023. Springer Nature Limited.)- Published
- 2023
- Full Text
- View/download PDF
16. Oral verrucous Carcinoma on mandibular right alveolar region.
- Author
-
Ravichandar R, Thirunavukarasu S, Reddy J, and Ramanujam S
- Subjects
- Humans, Lip, Mouth Neoplasms diagnosis, Mouth Neoplasms surgery, Lip Neoplasms, Carcinoma, Verrucous diagnosis, Carcinoma, Verrucous surgery, Carcinoma, Squamous Cell diagnostic imaging, Carcinoma, Squamous Cell surgery
- Abstract
Verrucous carcinoma, a low-grade variant of squamous cell carcinoma, defined as a diagnostically squamous cell neoplasia involving lip, oropharyngeal, and laryngeal mucosa and named as 'Ackerman's tumour' by Ackerman in 1948. It usually occurs in the lower lip region and this is one such case in which a painful proliferative growth was evident over the right alveolar region for the period of 8 months. Radiological investigations, biopsies were performed followed by surgical excision of the lesion., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2023. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2023
- Full Text
- View/download PDF
17. Metal-Organic Framework-Derived Mesoporous B-Doped CoO/Co@N-Doped Carbon Hybrid 3D Heterostructured Interfaces with Modulated Cobalt Oxidation States for Alkaline Water Splitting.
- Author
-
Cha DC, Singh TI, Maibam A, Kim TH, Nam DH, Babarao R, and Lee S
- Abstract
Heteroatom-doped transition metal-oxides of high oxygen evolution reaction (OER) activities interfaced with metals of low hydrogen adsorption energy barrier for efficient hydrogen evolution reaction (HER) when uniformly embedded in a conductive nitrogen-doped carbon (NC) matrix, can mitigate the low-conductivity and high-agglomeration of metal-nanoparticles in carbon matrix and enhances their bifunctional activities. Thus, a 3D mesoporous heterostructure of boron (B)-doped cobalt-oxide/cobalt-metal nanohybrids embedded in NC and grown on a Ni foam substrate (B-CoO/Co@NC/NF) is developed as a binder-free bifunctional electrocatalyst for alkaline water-splitting via a post-synthetic modification of the metal-organic framework and subsequent annealing in different Ar/H
2 gas ratios. B-CoO/Co@NC/NF prepared using 10% H2 gas (B-CoO/Co@NC/NF [10% H2 ]) shows the lowest HER overpotential (196 mV) and B-CoO/Co@NC/NF (Ar), developed in Ar, shows an OER overpotential of 307 mV at 10 mA cm-2 with excellent long-term durability for 100 h. The best anode and cathode electrocatalyst-based electrolyzer (B-CoO/Co@NC/NF (Ar)(+)//B-CoO/Co@NC/NF (10% H2 )(-)) generates a current density of 10 mA cm-2 with only 1.62 V with long-term stability. Further, density functional theory investigations demonstrate the effect of B-doping on electronic structure and reaction mechanism of the electrocatalysts for optimal interaction with reaction intermediates for efficient alkaline water-splitting which corroborates the experimental results., (© 2023 Wiley-VCH GmbH.)- Published
- 2023
- Full Text
- View/download PDF
18. Acoustomicrofluidic Defect Engineering and Ligand Exchange in ZIF-8 Metal-Organic Frameworks.
- Author
-
Massahud E, Ahmed H, Babarao R, Ehrnst Y, Alijani H, Darmanin C, Murdoch BJ, Rezk AR, and Yeo LY
- Abstract
A way through which the properties of metal-organic frameworks (MOFs) can be tuned is by engineering defects into the crystal structure. Given its intrinsic stability and rigidity, however, it is difficult to introduce defects into zeolitic imidazolate frameworks (ZIFs)-and ZIF-8, in particular-without compromising crystal integrity. In this work, it is shown that the acoustic radiation pressure as well as the hydrodynamic stresses arising from the oscillatory flow generated by coupling high frequency (MHz-order) hybrid surface and bulk acoustic waves into a suspension of ZIF-8 crystals in a liquid pressure transmitting medium is capable of driving permanent structural changes in their crystal lattice structure. Over time, the enhancement in the diffusive transport of guest molecules into the material's pores as a consequence is shown to lead to expansion of the pore framework, and subsequently, the creation of dangling-linker and missing-linker defects, therefore offering the possibility of tuning the type and extent of defects engineered into the MOF through the acoustic exposure time. Additionally, the practical utility of the technology is demonstrated for one-pot, simultaneous solvent-assisted ligand exchange under ambient conditions, for sub-micron-dimension ZIF-8 crystals and relatively large ligands-more specifically 2-aminobenzimidazole-without compromising the framework porosity or overall crystal structure., (© 2023 The Authors. Small Methods published by Wiley-VCH GmbH.)
- Published
- 2023
- Full Text
- View/download PDF
19. High-Alkaline Water-Splitting Activity of Mesoporous 3D Heterostructures: An Amorphous-Shell@Crystalline-Core Nano-Assembly of Co-Ni-Phosphate Ultrathin-Nanosheets and V- Doped Cobalt-Nitride Nanowires.
- Author
-
Singh TI, Maibam A, Cha DC, Yoo S, Babarao R, Lee SU, and Lee S
- Abstract
Introducing amorphous and ultrathin nanosheets of transition bimetal phosphate arrays that are highly active in the oxygen evolution reaction (OER) as shells over an electronically modulated crystalline core with low hydrogen absorption energy for an excellent hydrogen evolution reaction (HER) can boost the sluggish kinetics of the OER and HER in alkaline electrolytes. Therefore, in this study, ultrathin and amorphous cobalt-nickel-phosphate (CoNiPO
x ) nanosheet arrays are deposited over vanadium (V)-doped cobalt-nitride (V3% -Co4 N) crystalline core nanowires to obtain amorphous-shell@crystalline-core mesoporous 3D-heterostructures (CoNiPOx @V-Co4 N/NF) as bifunctional electrocatalysts. The optimized electrocatalyst shows extremely low HER and OER overpotentials of 53 and 270 mV at 10 mA cm-2 , respectively. The CoNiPOx @V3% -Co4 N/NF (+/-) electrolyzer utilizing the electrocatalyst as both anode and cathode demonstrates remarkable overall water-splitting activity, requiring a cell potential of only 1.52 V at 10 mA cm-2 , 30 mV lower than that of the RuO2 /NF (+)/20%-Pt/C/NF (-) electrolyzer. Such impressive bifunctional activities can be attributed to abundant active sites, adjusted electronic structure, lower charge-transfer resistance, enhanced electrochemically active surface area (ECSA), and surface- and volume-confined electrocatalysis resulting from the synergistic effects of the crystalline V3% -Co4 N core and amorphous CoNiPOx shells boosting water splitting in alkaline media., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)- Published
- 2022
- Full Text
- View/download PDF
20. Hetero-metallic metal-organic frameworks for room-temperature NO 2 sensing.
- Author
-
Khan MW, Sadiq MM, Gopalsamy K, Xu K, Jannat A, Zhang BY, Mohiuddin M, Haris M, Ou R, Afrin S, Alkathiri T, Loomba S, Mulet X, Mahmood N, Babarao R, and Ou JZ
- Abstract
Metal-organic frameworks (MOFs) with exceptional features such as high structural diversity and surface area as well as controlled pore size has been considered a promising candidate for developing room temperature highly-sensitive gas sensors. In comparison, the hetero-metallic MOFs with redox-active open-metal sites and mixed metal nodes may create peculiar surface properties and synergetic effects for enhanced gas sensing performances. In this work, the Fe atoms in the Fe
3 (Porous coordination network) PCN-250 MOFs are partially replaced by transition metal Co, Mn, and Zn through a facile hydrothermal approach, leading to the formation of hetero-metallic MOFs (Fe2 III MII , M = Co, Mn, and Zn). While the PCN-250 framework is maintained, the morphological and electronic band structural properties are manipulated upon the partial metal replacement of Fe. More importantly, the room temperature NO2 sensing performances are significantly varied, in which Fe2 Mn PCN-250 demonstrates the largest response magnitude for ppb-level NO2 gas compared to those of pure Fe3 PCN-250 and other hetero-metallic MOF structures mainly attributed to the highest binding energy of NO2 gas. This work demonstrates the strong potential of hetero-metallic MOFs with carefully engineered substituted metal clusters for power-saving and high-performance gas sensing applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)- Published
- 2022
- Full Text
- View/download PDF
21. Three-in-One C 2 H 2 -Selectivity-Guided Adsorptive Separation across an Isoreticular Family of Cationic Square-Lattice MOFs.
- Author
-
Dutta S, Mukherjee S, Qazvini OT, Gupta AK, Sharma S, Mahato D, Babarao R, and Ghosh SK
- Abstract
Energy-efficient selective physisorption driven C
2 H2 separation from industrial C2-C1 impurities such as C2 H4 , CO2 and CH4 is of great importance in the purification of downstream commodity chemicals. We address this challenge employing a series of isoreticular cationic metal-organic frameworks, namely iMOF-nC (n=5, 6, 7). All three square lattice topology MOFs registered higher C2 H2 uptakes versus the competing C2-C1 gases (C2 H4 , CO2 and CH4 ). Dynamic column breakthrough experiments on the best-performing iMOF-6C revealed the first three-in-one C2 H2 adsorption selectivity guided separation of C2 H2 from 1:1 C2 H2 /CO2 , C2 H2 /C2 H4 and C2 H2 /CH4 mixtures. Density functional theory calculations critically examined the C2 H2 selective interactions in iMOF-6C. Thanks to the abundance of square lattice topology MOFs, this study introduces a crystal engineering blueprint for designing C2 H2 -selective layered metal-organic physisorbents, previously unreported in cationic frameworks., (© 2021 Wiley-VCH GmbH.)- Published
- 2022
- Full Text
- View/download PDF
22. Prediction of O 2 /N 2 Selectivity in Metal-Organic Frameworks via High-Throughput Computational Screening and Machine Learning.
- Author
-
Orhan IB, Daglar H, Keskin S, Le TC, and Babarao R
- Abstract
Machine learning (ML), which is becoming an increasingly popular tool in various scientific fields, also shows the potential to aid in the screening of materials for diverse applications. In this study, the computation-ready experimental (CoRE) metal-organic framework (MOF) data set for which the O
2 and N2 uptakes, self-diffusivities, and Henry's constants were calculated was used to fit the ML models. The obtained models were subsequently employed to predict such properties for a hypothetical MOF (hMOF) data set and to identify structures having a high O2 /N2 selectivity at room temperature. The performance of the model on known entries indicated that it would serve as a useful tool for the prediction of MOF characteristics with r2 correlations between the true and predicted values typically falling between 0.7 and 0.8. The use of different descriptor groups (geometric, atom type, and chemical) was studied; the inclusion of all descriptor groups yielded the best overall results. Only a small number of entries surpassed the performance of those in the CoRE MOF set; however, the use of ML was able to present the structure-property relationship and to identity the top performing hMOFs for O2 /N2 separation based on the adsorption and diffusion selectivity.- Published
- 2022
- Full Text
- View/download PDF
23. Glioblastoma multiforme of spinal cord - Case series in a tertiary cancer centre.
- Author
-
Nagarajan A and Ravichandar R
- Abstract
Background and Aim: Primary spinal cord glioblastoma multiforme (GBM) is a rare clinical condition and is often associated with a dismal prognosis. The standard treatment is maximal safe surgery followed by adjuvant radiotherapy and chemotherapy. Despite such aggressive treatments, the median survival is estimated to be around 15 months in several studies. We report three patients with primary spinal GBM who received treatment in our institute from 2012 to 2019. Among the three, one patient is on long-term follow-up with no evidence of disease, another patient succumbed to the illness and the third patient is having stable disease., Relevance for Patients: Although primary spinal GBM is usually associated with a dismal prognosis, our case series shows a subset of patients will have a favorable outcome with the protocol treatment., Competing Interests: The authors declare no conflict of interest., (Copyright: © Whioce Publishing Pte. Ltd.)
- Published
- 2021
24. Definitive chemoradiation in locally advanced inoperable esophageal cancer patients - Retrospective analysis of different chemotherapy regimens in a tertiary cancer centre.
- Author
-
Nagarajan A, Nureja BY, Ravichandar R, and Ranganathan R
- Abstract
Background and Aim: Definitive chemoradiation (dCRT) is the standard treatment for locally advanced inoperable esophageal cancer. The aim of this study is to analyze the effect of dCRT combined with paclitaxel and carboplatin (TC) against cisplatin (CDDP) with radiation., Methods: The study population included patients with locally advanced inoperable esophageal cancer seeking treatment at our center from March 2013 to December 2017. Case records from 66 patients were extracted. The toxicity profile of patients who received TC or CDDP was reported and analyzed. A Chi-square test and students t-test were used to analyze the categorical, and the continuous variables, respectively. The KaplanMeier method was used to estimate the survival probability. A log-rank test was applied to compare the survival differences between the two groups., Results: The overall survival (OS) did not differ at 3 years between the TC and CDDP (p = 0.286). The median survival duration was 13 months for CDDP and 18 months for TC. The toxicity profile like emesis (93% CDDP vs. 25% TC), neutropenia (79% CDDP vs. 13% TC), thrombocytopenia (10% CDDP vs. 17% TC) and dyselectrolytemia (71% CDDP vs. 8% TC) were compared between the two treatment groups and found to be more in CDDP group., Conclusion: The treatment of patients with locally advanced esophageal carcinoma with dCRT and TC showed an improved toxicity profile, but similar OS compared to CDDP. Applying dCRT with TC could be an alternate regimen for locally advanced inoperable esophageal cancer patients., Relevance for Patients: Concurrent chemoradiation with TC regimen can be considered as an alternative for cisplatin as it shows equivalent survival and reduced toxicity profile., Competing Interests: The authors declare no conflict of interest., (Copyright: © Whioce Publishing Pte. Ltd.)
- Published
- 2021
25. Elucidating the mechanisms of Paraffin-Olefin separations using nanoporous adsorbents: An overview.
- Author
-
Saha D, Kim MB, Robinson AJ, Babarao R, and Thallapally PK
- Abstract
Light olefins are the precursors of all modern-day plastics. Olefin is always mixed with paraffins in the time of production, and therefore it needs to be separated from paraffins to produce polymer-grade olefin. The state-of-the-art separation technique, cryogenic distillation, is highly expensive and hazardous. Adsorption could be a novel, sustainable, and inexpensive separation strategy, provided a suitable adsorbent can be designed. There are different types of mechanisms that were harnessed for the separation of olefins by adsorption, and in this review, we have focused our discussion on those mechanisms. These mechanisms include, (a) Affinity-based separation, like pi complexation and hydrogen bonding, (b) Separation based on pore size and shape, like size-exclusion and gate-opening effect, and (c) Non-equilibrium separation, like kinetic separation. In this review, we have elaborated each of the separation strategies from the fundamental level and explained their roles in the separation processes of different types of paraffins and olefins., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)
- Published
- 2021
- Full Text
- View/download PDF
26. Reversing Benzene/Cyclohexane Selectivity through Varying Supramolecular Interactions Using Aliphatic, Isoreticular MOFs.
- Author
-
Macreadie LK, Qazvini OT, and Babarao R
- Abstract
Effective solid-state adsorbent materials, such as metal organic frameworks (MOFs), rely upon tailored void spaces for selective adsorption of one component from a mixture. This is particularly crucial when separating challenging mixtures such as benzene (Bz) and cyclohexane (Cy) requiring a highly expensive and energy intensive process. Employing bulky "3D-linkers" to construct MOFs leads to materials with unique, contoured pore shapes which consequently allow for significant control over guest adsorption preferences. Investigation into these selectivity preferences is key to identifying suitable materials for industrial separations and is an area currently underexplored. Here, we provide an in-depth investigation exploring the selectivity path between planar and 3D-linkers and their preference to adsorb either Cy or Bz. To validate this principle, the adsorption selectivity of Cy and Bz in 3DL-MOF-1 ([Zn
4 O(pdc)3 ] (pdc = bicylo[1.1.1]pentane-1,3-dicarboxylate), CUB-5, and MOF-5 was explored. MOF-5 exhibits a selective preference for Cy adsorption at low pressures, contrary to popular belief, while CUB-5 and 3DL-MOF-1 are Bz selective. DFT-D3 calculations and breakthrough simulations explore this behavior and highlight CUB-5 and MOF-5 as strong candidates for future separation materials.- Published
- 2021
- Full Text
- View/download PDF
27. Plasmonic metal-organic framework nanocomposites enabled by degenerately doped molybdenum oxides.
- Author
-
Khan MW, Zhang BY, Xu K, Mohiuddin M, Jannat A, Haque F, Alkathiri T, Pillai N, Wang Y, Reza SZ, Li J, Mulet X, Babarao R, Mahmood N, and Ou JZ
- Abstract
Metal-organic frameworks (MOFs) nanocomposites are under the limelight due to their unique electronic, optical, and surface properties for various applications. Plasmonic MOFs enabled by noble metal nanostructures are an emerging class of MOF nanocomposites with efficient solar light-harvesting capability. However, major concerns such as poor photostability, sophisticated synthesis processes, and high fabrication cost are raised. Here, we develop a novel plasmonic MOF nanocomposite consisting of the ultra-thin degenerately doped molybdenum oxide core and the flexible iron MOF (FeMOF) shell through a hydrothermal growth, featuring low cost, facile synthesis, and non-toxicity. More importantly, the incorporation of plasmonic oxides in the highly porous MOF structure enhances the visible light absorbability, demonstrating improved photobleaching performances of various azo and non-azo dyes compared to that of pure FeMOF without the incorporation of oxidative agents. Furthermore, the nanocomposite exhibits enhanced sensitivity and selectivity towards NO
2 gas at room temperature, attributed to the electron-rich surface of plasmonic oxides. This work possibly broadens the exploration of plasmonic MOF nanocomposites for practical and efficient solar energy harvesting, environmental remediation, and environmental monitoring applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)- Published
- 2021
- Full Text
- View/download PDF
28. Nimotuzumab combined with radiotherapy for the treatment of hypopharyngeal cancer - A case report from a tertiary cancer center.
- Author
-
Nagarajan A, Sakthivelu A, Santhanaraman N, and Ravichandar R
- Abstract
Background: Nimotuzumab is a monoclonal antibody against epidermal growth factor receptor which can be combined with chemotherapy and radiotherapy for the treatment of locally advanced unresectable squamous cell carcinoma of head-and-neck region and its role has already been established in India., Aim: The aim of this case report is to show the role of nimotuzumab in carcinoma hypopharynx., Methods: We report a patient with Stage III carcinoma of hypopharynx, who received radiotherapy along with weekly nimotuzumab due to his comorbidities. The patient had tolerated the treatment very well without any major side effects., Results: The patient is on regular follow-up with a complete response (CR) of the disease and with the disease-free interval (DFI) of 7 months., Conclusions: Nimotuzumab along with radiotherapy can be safely given in the patients with carcinoma hypopharynx, who are ineligible for chemotherapy., Relevance for Patients: Nimotuzumab can be added with radiotherapy to the patients with head-and-neck malignancies who are ineligible for chemotherapy to improve the clinical outcome with minimal toxicity., Competing Interests: The authors declare no conflicts of interest., (Copyright: © Whioce Publishing Pte. Ltd.)
- Published
- 2021
29. Heparanome-Mediated Rescue of Oligodendrocyte Progenitor Quiescence following Inflammatory Demyelination.
- Author
-
Saraswat D, Welliver RR, Ravichandar R, Tripathi A, Polanco JJ, Broome J, Hurley E, Dutta R, Feltri ML, and Sim FJ
- Subjects
- Animals, Cell Differentiation physiology, Cell Proliferation physiology, Demyelinating Autoimmune Diseases, CNS pathology, Demyelinating Diseases metabolism, Demyelinating Diseases pathology, Humans, Inflammation metabolism, Inflammation pathology, Mice, Mice, Knockout, Demyelinating Autoimmune Diseases, CNS metabolism, Heparan Sulfate Proteoglycans metabolism, Interferon-gamma metabolism, Oligodendrocyte Precursor Cells metabolism
- Abstract
The proinflammatory cytokine IFN-γ, which is chronically elevated in multiple sclerosis, induces pathologic quiescence in human oligodendrocyte progenitor cells (OPCs) via upregulation of the transcription factor PRRX1. In this study using animals of both sexes, we investigated the role of heparan sulfate proteoglycans in the modulation of IFN-γ signaling following demyelination. We found that IFN-γ profoundly impaired OPC proliferation and recruitment following adult spinal cord demyelination. IFN-γ-induced quiescence was mediated by direct signaling in OPCs as conditional genetic ablation of IFN γ R1 ( Ifngr1 ) in adult NG2
+ OPCs completely abrogated these inhibitory effects. Intriguingly, OPC-specific IFN-γ signaling contributed to failed oligodendrocyte differentiation, which was associated with hyperactive Wnt/Bmp target gene expression in OPCs. We found that PI-88, a heparan sulfate mimetic, directly antagonized IFN-γ to rescue human OPC proliferation and differentiation in vitro and blocked the IFN-γ-mediated inhibitory effects on OPC recruitment in vivo Importantly, heparanase modulation by PI-88 or OGT2155 in demyelinated lesions rescued IFN-γ-mediated axonal damage and demyelination. In addition to OPC-specific effects, IFN-γ-augmented lesions were characterized by increased size, reactive astrogliosis, and proinflammatory microglial/macrophage activation along with exacerbated axonal injury and cell death. Heparanase inhibitor treatment rescued many of the negative IFN-γ-induced sequelae suggesting a profound modulation of the lesion environment. Together, these results suggest that the modulation of the heparanome represents a rational approach to mitigate the negative effects of proinflammatory signaling and rescuing pathologic quiescence in the inflamed and demyelinated human brain. SIGNIFICANCE STATEMENT The failure of remyelination in multiple sclerosis contributes to neurologic dysfunction and neurodegeneration. The activation and proliferation of oligodendrocyte progenitor cells (OPCs) is a necessary step in the recruitment phase of remyelination. Here, we show that the proinflammatory cytokine interferon-γ directly acts on OPCs to induce pathologic quiescence and thereby limit recruitment following demyelination. Heparan sulfate is a highly structured sulfated carbohydrate polymer that is present on the cell surface and regulates several aspects of the signaling microenvironment. We find that pathologic interferon-γ can be blocked by modulation of the heparanome following demyelination using either a heparan mimetic or by treatment with heparanase inhibitor. These studies establish the potential for modulation of heparanome as a regenerative approach in demyelinating disease., (Copyright © 2021 the authors.)- Published
- 2021
- Full Text
- View/download PDF
30. Selective capture of carbon dioxide from hydrocarbons using a metal-organic framework.
- Author
-
Qazvini OT, Babarao R, and Telfer SG
- Abstract
Efficient and sustainable methods for carbon dioxide capture are highly sought after. Mature technologies involve chemical reactions that absorb CO
2, but they have many drawbacks. Energy-efficient alternatives may be realised by porous physisorbents with void spaces that are complementary in size and electrostatic potential to molecular CO2 . Here, we present a robust, recyclable and inexpensive adsorbent termed MUF-16. This metal-organic framework captures CO2 with a high affinity in its one-dimensional channels, as determined by adsorption isotherms, X-ray crystallography and density-functional theory calculations. Its low affinity for other competing gases delivers high selectivity for the adsorption of CO2 over methane, acetylene, ethylene, ethane, propylene and propane. For equimolar mixtures of CO2 /CH4 and CO2 /C2 H2 , the selectivity is 6690 and 510, respectively. Breakthrough gas separations under dynamic conditions benefit from short time lags in the elution of the weakly-adsorbed component to deliver high-purity hydrocarbon products, including pure methane and acetylene.- Published
- 2021
- Full Text
- View/download PDF
31. Mixed donor, phenanthroline photoactive MOFs with favourable CO 2 selectivity.
- Author
-
Setter CJ, Price MB, Conte L, Schmitt W, Batten SR, Richardson C, Hill MR, Babarao R, and Macreadie LK
- Abstract
Mixed donor phenanthroline-carboxylate linkers were combined with Mn
II or ZnII to form photoactive MOFs with large pore apertures. The MOFs display high CO2 adsorption capacities, which consequently causes structural framework flexibility, and align with favorable metrics for selective CO2 capture. The photophysical properties of the MOFs were investigated, with the MnII MOF giving rise to short triplet LMCT lifetimes.- Published
- 2020
- Full Text
- View/download PDF
32. A Water-Stable Cationic Metal-Organic Framework with Hydrophobic Pore Surfaces as an Efficient Scavenger of Oxo-Anion Pollutants from Water.
- Author
-
Dutta S, Samanta P, Joarder B, Let S, Mahato D, Babarao R, and Ghosh SK
- Abstract
Water contamination due to heavy metal-based toxic oxo-anions (such as CrO
4 2- and TcO4 - ) is a critical environmental concern that demands immediate mitigation. Herein, we present an effort to counter this issue by a novel chemically stable cationic metal-organic framework (iMOF-2C) with strategic utilization of a ligand with hydrophobic core, known to facilitate such oxo-anion capture process. Moreover, the compound exhibited very fast sieving kinetics for such oxo-anions and a very high uptake capacity for CrO4 2- (476.3 mg g-1 ) and ReO4 - (691 mg g-1 ), while the latter being employed as a surrogate analogue for radioactive TcO4 - anions. Notably, the compound showed excellent selectivity even in the presence of other competing anions such as NO3 - , Cl- , SO4 2- , ClO4 - . etc.. Furthermore, the compound possesses excellent reusability (up to 10 cycles) and is also employed to a stationary phase ion column to decontaminate the aforementioned oxo-anions from water.- Published
- 2020
- Full Text
- View/download PDF
33. The Effect of Sterically Active Ligand Substituents on Gas Adsorption within a Family of 3D Zn-Based Coordination Polymers.
- Author
-
Abrahams BF, Babarao R, Dharma AD, Holmes JL, Hudson TA, Maynard-Casely HE, McGain F, Robson R, and White KF
- Abstract
An investigation of the adsorption properties of two structurally related, 3D coordination polymers of composition Zn(2-Mehba) and Zn(2,6-Me
2 hba) (2-Mehba = the dianion of 2-methyl-4-hydroxybenzoic acid and 2,6-Me2 hba = the dianion of 2,6-dimethyl-4-hydroxybenzoic acid) is presented. A common feature of these structures are parallel channels that are able to accommodate appropriately sized guest molecules. The structures differ with respect to the steric congestion within the channels arising from methyl groups appended to the bridging ligands of the network. The host network, Zn(2-Mehba), is able to take up appreciable quantities of H2 (77 K) and CO2 and CH4 (298 K) in a reversible manner. In regard to the adsorption of N2 by Zn(2-Mehba), there appears to be an unusual temperature dependence for the uptake of the gas such that when the temperature is increased from 77 to 298 K the uptake of N2 increases. The relatively narrow channels of Zn(2,6-Me2 hba) are too small to allow the uptake of N2 and CH4 , but H2 molecules can be adsorbed. A pronounced step at elevated pressures in CO2 and N2 O isotherms for Zn(2,6-Me2 hba) is noted. Calculations indicate that rotation of phenolate rings leads to a change in the available intraframework space during CO2 dosing.- Published
- 2020
- Full Text
- View/download PDF
34. Metal-Organic Framework-Enhanced Solid-Phase Microextraction Mass Spectrometry for the Direct and Rapid Detection of Perfluorooctanoic Acid in Environmental Water Samples.
- Author
-
Suwannakot P, Lisi F, Ahmed E, Liang K, Babarao R, Gooding JJ, and Donald WA
- Abstract
We report the development of metal-organic framework (MOF)-based probes for the direct and rapid detection and quantification of perfluorooctanoic acid (PFOA) by mass spectrometry. Four water-resistant MOFs-ZIF-8, UiO-66, MIL88-A, and Tb
2 (BDC)3 -were coated on poly(dopamine) precoated stainless steel needles and used to rapidly preconcentrate PFOA from water for direct analysis by nanoelectrospray ionization mass spectrometry. The analytical performance of each MOF for detecting PFOA was correlated with both the calculated binding energy of the MOF for PFOA and the relative change in the surface area of the MOF upon exposure to PFOA. MOF-functionalized probes can be used for the rapid (<5 min) and sensitive quantification of PFOA molecules at low ng L-1 levels in environmental water samples (i.e., tap water, rainwater, and seawater) with no sample preparation. The limit of detection of PFOA in ultrapure water was 11.0 ng L-1 . Comparable accuracy to an accredited analytical method was achieved, despite the MOF-functionalized probe approach being ∼40 times quicker and requiring ∼10 times less sample. These features indicate that MOF-coated probes are promising for the direct and rapid monitoring of polyfluorinated substances and other pollutants in the field.- Published
- 2020
- Full Text
- View/download PDF
35. Enhancing Multicomponent Metal-Organic Frameworks for Low Pressure Liquid Organic Hydrogen Carrier Separations.
- Author
-
Macreadie LK, Babarao R, Setter CJ, Lee SJ, Qazvini OT, Seeber AJ, Tsanaktsidis J, Telfer SG, Batten SR, and Hill MR
- Abstract
The resurgence of interest in the hydrogen economy could hinge on the distribution of hydrogen in a safe and efficient manner. Whilst great progress has been made with cryogenic hydrogen storage or liquefied ammonia, liquid organic hydrogen carriers (LOHCs) remain attractive due to their lack of need for cryogenic temperatures or high pressures, most commonly a cycle between methylcyclohexane and toluene. Oxidation of methylcyclohexane to release hydrogen will be more efficient if the equilibrium limitations can be removed by separating the mixture. This report describes a family of six ternary and quaternary multicomponent metal-organic frameworks (MOFs) that contain the three-dimensional cubane-1,4-dicarboxylate (cdc) ligand. Of these MOFs, the most promising is a quaternary MOF (CUB-30), comprising cdc, 4,4'-biphenyldicarboxylate (bpdc) and tritopic truxene linkers. Contrary to conventional wisdom that adsorptive interactions with larger, hydrocarbon guests are dominated by π-π interactions, here we report that contoured aliphatic pore environments can exhibit high selectivity and capacity for LOHC separations at low pressures. This is the first time, to the best of our knowledge, where selective adsorption for cyclohexane over benzene is witnessed, underlining the unique adsorptive behavior afforded by the unconventional cubane moiety., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2020
- Full Text
- View/download PDF
36. On/off porosity switching and post-assembly modifications of Cu 4 L 4 metal-organic polyhedra.
- Author
-
Bloch WM, Babarao R, and Schneider ML
- Abstract
Synthetic porous materials composed of metal-organic polyhedra (MOPs) have found application in topical areas such as gas storage, separation and catalysis. Control over their physical properties ( e.g. porosity) has typically been achieved through ligand design or judicious choice of metal ions. Here, we demonstrate pore-size control and on/off porosity in Cu
4 L4 MOPs by exploiting their structural non-rigidity. We report an aldehyde-functionalised MOP ( 1 ) that can be isolated in five distinct solvatomorphs, each exhibiting different structural flexibility. When soaked in MeOH, two of these solvatomorphs undergo a rapid transformation to a thermodynamically favoured phase, whilst in acetone they template the crystallisation of an entirely new crystal packing. We support these findings by single and powder X-ray diffraction and rationalise the observed phase transformations by lattice energy calculations. Of the five solvatomorphs, three can be obtained as solvent-exchanged pseudo-polymorphs with distinct porosities in their activated form (SABET = 35-455 m2 g-1 ). Further control over the crystal packing of MOPs is achieved through covalent post-assembly modifications, which promote the crystallisation of isoreticular 2-D sheet-like structures., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)- Published
- 2020
- Full Text
- View/download PDF
37. Design, synthesis and biological evaluation of theophylline containing variant acetylene derivatives as α-amylase inhibitors.
- Author
-
Ruddarraju RR, Kiran G, Murugulla AC, Maroju R, Prasad DK, Kumar BH, Bakshi V, and Reddy NS
- Subjects
- Acarbose standards, Animals, Binding Sites, Blood Glucose drug effects, Diabetes Mellitus, Experimental, Diet, High-Fat, Drug Evaluation, Preclinical, Glycoside Hydrolase Inhibitors pharmacology, Hypoglycemic Agents pharmacology, Male, Molecular Docking Simulation, Molecular Structure, Pioglitazone pharmacology, Protein Binding, Rats, Streptozocin metabolism, Structure-Activity Relationship, Theophylline pharmacology, Acetylene chemistry, Glycoside Hydrolase Inhibitors chemical synthesis, Hypoglycemic Agents chemical synthesis, Theophylline chemical synthesis, alpha-Amylases antagonists & inhibitors
- Abstract
A novel pharmacophore with theophylline and acetylene moieties was constructed by using a fragment-based drug design and a series of twenty theophylline containing acetylene conjugates were designed and synthesized, and all the compounds were evaluated by enzyme-based in vitro α-amylase inhibition activity. The in vitro evaluation revealed that most of the compounds displayed good inhibitory activities, and among them nine analogs 13-15, 20, 21 and 24-27 were exhibited more or nearly as equipotent inhibitory activity with IC
50 values 1.11 ± 0.07, 1.14 ± 0.17, 1.07 ± 0.01 and 1.21 ± 0.03, 1.33 ± 0.09, 1.17 ± 0.01, 1.05 ± 0.02, 1.61 ± 0.04, 1.02 ± 0.03 μM respectively, as compared with standard, acarbose 1.37 ± 0.26 μM. Further, molecular docking simulation studies were done to identify the interactions and binding mode of synthesized analogs at binding site of α-amylase enzyme (PBD ID: 4GQR). Among the synthesized analogs, two compounds 25 and 27 were selected on the basis of α-amylase inhibition activity and evaluated for in vivo anti-diabetic activity by High Fat Diet-Streptozotocin (HFD-STZ) model in normal rats. At the dose of 10 mg/kg, bw, po these compounds have significantly reduced Plasma Glucose level in rats as compared to pioglitazone. The anti-diabetic activity results showed that the animal treated with the compounds 25 and 27 could better reverse and control the progression of the disease compared to the standard., (Copyright © 2019 Elsevier Inc. All rights reserved.)- Published
- 2019
- Full Text
- View/download PDF
38. Acoustomicrofluidic assembly of oriented and simultaneously activated metal-organic frameworks.
- Author
-
Ahmed H, Rezk AR, Richardson JJ, Macreadie LK, Babarao R, Mayes ELH, Lee L, and Yeo LY
- Abstract
The high surface area and porosity, and limitless compound and network combinations between the metal ions and organic ligands making up metal-organic frameworks (MOFs) offer tremendous opportunities for their use in many applications. While numerous methods have been proposed for the synthesis of MOF powders, it is often difficult to obtain oriented crystals with these techniques. Further, the need for additional post-synthesis steps to activate the crystals and release them from the substrate presents a considerable production challenge. Here, we report an acoustically-driven microcentrifugation platform that facilitates fast convective solutal transport, allowing the synthesis of MOF crystals in as short as five minutes. The crystals are not only oriented due to long-range out-of-plane superlattice ordering aided by molecular dipole polarization under the acoustoelectric coupling, but also simultaneously activated during the synthesis process.
- Published
- 2019
- Full Text
- View/download PDF
39. A Robust Ethane-Trapping Metal-Organic Framework with a High Capacity for Ethylene Purification.
- Author
-
Qazvini OT, Babarao R, Shi ZL, Zhang YB, and Telfer SG
- Abstract
The separation of ethane from ethylene is of prime importance in the purification of chemical feedstocks for industrial manufacturing. However, differentiating these compounds is notoriously difficult due to their similar physicochemical properties. High-performance porous adsorbents provide a solution. Conventional adsorbents trap ethylene in preference to ethane, but this incurs multiple steps in separation processes. Alternatively, high-purity ethylene can be obtained in a single step if the adsorbent preferentially adsorbs ethane over ethylene. We herein report a metal-organic framework, MUF-15 (MUF, Massey University Framework), constructed from inexpensive precursors that sequesters ethane from ethane/ethylene mixtures. The productivity of this material is exceptional: 1 kg of MOF produces 14 L of polymer-grade ethylene gas in a single adsorption step starting from an equimolar ethane/ethylene mixture. Computational simulations illustrate the underlying mechanism of guest adsorption. The separation performance was assessed by measuring multicomponent breakthrough curves, which illustrate that the separation performance is maintained over a wide range of feed compositions and operating pressures. MUF-15 is robust, maintains its performance in the presence of acetylene, and is easily regenerated by purging with inert gas or by placing under reduced pressure.
- Published
- 2019
- Full Text
- View/download PDF
40. CUB-5: A Contoured Aliphatic Pore Environment in a Cubic Framework with Potential for Benzene Separation Applications.
- Author
-
Macreadie LK, Mensforth EJ, Babarao R, Konstas K, Telfer SG, Doherty CM, Tsanaktsidis J, Batten SR, and Hill MR
- Abstract
One prominent aspect of metal organic frameworks (MOFs) is the ability to tune the size, shape, and chemical characteristics of their pores. MOF-5, with its open cubic connectivity of Zn
4 O clusters joined by two-dimensional, terephthalate linkers, is the archetypal example: both functionalized and elongated linkers produce isoreticular frameworks that define pores with new shapes and chemical environments. The recent scalable synthesis of cubane-1,4-dicarboxylic acid (1,4-H2 cdc) allows the first opportunity to explore its application in leading reticular architectures. Herein we describe the use of 1,4-H2 cdc to construct [Zn4 O(1,4-cdc)3 ], referred to as CUB-5. Isoreticular with MOF-5, CUB-5 adopts a cubic architecture but features aliphatic, rather than aromatic, pore surfaces. Methine units point directly into the pores, delivering new and unconventional adsorption locations. Our results show that CUB-5 is capable of selectively adsorbing high amounts of benzene at low partial pressures, promising for future investigations into the industrial separation of benzene from gasoline using aliphatic MOF materials. These results present an effective design strategy for the generation of new MOF materials with aliphatic pore environments and properties previously unattainable in conventional frameworks.- Published
- 2019
- Full Text
- View/download PDF
41. Multifunctional Behavior of Sulfonate-Based Hydrolytically Stable Microporous Metal-Organic Frameworks.
- Author
-
Desai AV, Joarder B, Roy A, Samanta P, Babarao R, and Ghosh SK
- Abstract
An isostructural pair of extremely rare, permanently microporous sulfonate-based metal-organic frameworks (MOFs) having a novel topology has been reported here by integration of rationally chosen building units. The compounds bear polar sites in the pore surfaces and exhibit selective adsorption of CO
2 , which features among the highest reported uptakes in the domain of organosulfonate-based MOFs. The compounds also exhibit multifunctionality for C6 -cyclic hydrocarbon separation and selective detection of neurotransmitter nitric oxide. Such multifunctional behavior on the basis of permanent porosity has been rarely observed for sulfonate-based MOFs. The efficacy of the synthesis approach is further highlighted by the resistance over a wide pH range and promising feasibility of reticular chemistry in porous organosulfonate-based systems.- Published
- 2018
- Full Text
- View/download PDF
42. Theranostic Probes for Targeting Tumor Microenvironment: An Overview.
- Author
-
Sikkandhar MG, Nedumaran AM, Ravichandar R, Singh S, Santhakumar I, Goh ZC, Mishra S, Archunan G, Gulyás B, and Padmanabhan P
- Subjects
- Animals, Diagnostic Imaging, Disease Models, Animal, Drug Delivery Systems, Humans, Mice, Neoplasms pathology, Neoplasms diagnosis, Neoplasms therapy, Theranostic Nanomedicine methods, Tumor Microenvironment
- Abstract
Long gone is the time when tumors were thought to be insular masses of cells, residing independently at specific sites in an organ. Now, researchers gradually realize that tumors interact with the extracellular matrix (ECM), blood vessels, connective tissues, and immune cells in their environment, which is now known as the tumor microenvironment (TME). It has been found that the interactions between tumors and their surrounds promote tumor growth, invasion, and metastasis. The dynamics and diversity of TME cause the tumors to be heterogeneous and thus pose a challenge for cancer diagnosis, drug design, and therapy. As TME is significant in enhancing tumor progression, it is vital to identify the different components in the TME such as tumor vasculature, ECM, stromal cells, and the lymphatic system. This review explores how these significant factors in the TME, supply tumors with the required growth factors and signaling molecules to proliferate, invade, and metastasize. We also examine the development of TME-targeted nanotheranostics over the recent years for cancer therapy, diagnosis, and anticancer drug delivery systems. This review further discusses the limitations and future perspective of nanoparticle based theranostics when used in combination with current imaging modalities like Optical Imaging, Magnetic Resonance Imaging (MRI) and Nuclear Imaging (Positron Emission Tomography (PET) and Single Photon Emission Computer Tomography (SPECT)).
- Published
- 2017
- Full Text
- View/download PDF
43. Design, synthesis, anticancer, antimicrobial activities and molecular docking studies of theophylline containing acetylenes and theophylline containing 1,2,3-triazoles with variant nucleoside derivatives.
- Author
-
Ruddarraju RR, Murugulla AC, Kotla R, Chandra Babu Tirumalasetty M, Wudayagiri R, Donthabakthuni S, Maroju R, Baburao K, and Parasa LS
- Subjects
- Anti-Infective Agents chemical synthesis, Anti-Infective Agents chemistry, Anti-Infective Agents metabolism, Anti-Infective Agents pharmacology, Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Antineoplastic Agents metabolism, Antineoplastic Agents pharmacology, Cell Line, Tumor, Cell Proliferation drug effects, Chemistry Techniques, Synthetic, Humans, Microbial Sensitivity Tests, Molecular Docking Simulation, Protein Conformation, Quantitative Structure-Activity Relationship, Triazoles chemistry, Triazoles metabolism, Vascular Endothelial Growth Factor Receptor-2 chemistry, Vascular Endothelial Growth Factor Receptor-2 metabolism, Alkynes chemistry, Drug Design, Nucleosides chemistry, Theophylline chemistry, Triazoles chemical synthesis, Triazoles pharmacology
- Abstract
A new series of theophylline containing acetylene derivatives (6a-6b and 7-13) and theophylline containing 1,2,3-triazoles with variant nucleoside derivatives (20-32) have been designed and synthesized. These compounds were screened for anticancer and antimicrobial activity. Further the computational docking and 2D QSAR were performed using MOE software to identify novel scaffolds. The results showed that compound 29 and 30 exhibit significant cytotoxic effect on all four cancer cells such as lung (A549), colon (HT-29), breast (MCF-7) and melanoma (A375) with IC50 values of 2.56, 2.19, 1.89, 4.89 μM and 3.57, 2.90, 2.10, 5.81 μM respectively. Whereas quite different results were observed for these compounds in antimicrobial studies. Compounds 11, 21 and 26 have exhibited significant minimum inhibitory concentrations (MIC) against Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa. The docking studies demonstrate that compound 27, 28, 29 and 30 have good dock score and binding affinities with various therapeutic targets in cancer cell proliferation. In addition these compounds have shown acceptable correlation with bioassay results in the regression plots generated in 2D QSAR models. This is the first report to demonstrate the theophylline containing acetylene derivatives and theophylline containing 1,2,3-triazole nucleoside hybrids as potential anticancer and antimicrobial agents with comprehensive in silico analysis., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
44. Design, synthesis, anticancer activity and docking studies of theophylline containing 1,2,3-triazoles with variant amide derivatives.
- Author
-
Ruddarraju RR, Murugulla AC, Kotla R, Tirumalasetty MCB, Wudayagiri R, Donthabakthuni S, and Maroju R
- Abstract
A new series of theophylline analogues containing 1,2,3-triazoles with different amide groups ( 22-41 ) has been designed and synthesized, and their biological activities have been evaluated as potential anticancer agents. The anticancer activities of the synthesized compounds were studied in four cancer cell lines viz. lung (A549), colon (HT-29), breast (MCF-7) and melanoma (A375). Furthermore, these compounds were screened for computational ADME and Lipinski's analysis followed by molecular docking and binding energy calculations against the various therapeutic targets involved in cell proliferation. The in vitro results demonstrate that compounds 22 , 27 , 36 and 40 have pivotal anticancer activity. Among these, compounds 22 and 27 have significant cytotoxic activity in all three cell lines; the in silico docking studies also reveal that compounds 22 , 27 and 36 have good dock scores, binding affinities and binding energies towards human epidermal growth factor receptor 2. This is the first report to demonstrate theophylline hybrids containing 1,2,3-triazoles as potential anticancer agents.
- Published
- 2016
- Full Text
- View/download PDF
45. Harnessing Lewis acidic open metal sites of metal-organic frameworks: the foremost route to achieve highly selective benzene sorption over cyclohexane.
- Author
-
Mukherjee S, Manna B, Desai AV, Yin Y, Krishna R, Babarao R, and Ghosh SK
- Abstract
π-Complexation triggered Lewis acid-base interactions between open metal sites (OMS) of metal-organic frameworks (MOFs), and π-e(-) rich adsorptive benzene (Bz) is exploited to establish M-MOF-74 as the best Bz-selective MOF sorbent, marking the first report of utilizing OMS behind benzene/cyclohexane separation; a key advance from the energy-economy standpoint of industrial separation.
- Published
- 2016
- Full Text
- View/download PDF
46. Facile stabilization of cyclodextrin metal-organic frameworks under aqueous conditions via the incorporation of C60 in their matrices.
- Author
-
Li H, Hill MR, Huang R, Doblin C, Lim S, Hill AJ, Babarao R, and Falcaro P
- Subjects
- Hydrophobic and Hydrophilic Interactions, Models, Molecular, Molecular Conformation, Carboxylic Acids chemistry, Fullerenes chemistry, Organometallic Compounds chemistry, Water chemistry, gamma-Cyclodextrins chemistry
- Abstract
A facile method to improve the stability of γ-cyclodextrin metal-organic frameworks (γ-CD-MOFs) in an aqueous environment has been developed through the incorporation of hydrophobic C60 in their matrices, and the resulting hybrid materials were exploited for drug delivery applications.
- Published
- 2016
- Full Text
- View/download PDF
47. Defect engineering of UiO-66 for CO2 and H2O uptake - a combined experimental and simulation study.
- Author
-
Liang W, Coghlan CJ, Ragon F, Rubio-Martinez M, D'Alessandro DM, and Babarao R
- Abstract
Defect concentrations and their compensating groups have been systematically tuned within UiO-66 frameworks by using modified microwave-assisted solvothermal methods. Both of these factors have a pronounced effect on CO2 and H2O adsorption at low and high pressure.
- Published
- 2016
- Full Text
- View/download PDF
48. A New Structural Family of Gas-Sorbing Coordination Polymers Derived from Phenolic Carboxylic Acids.
- Author
-
White KF, Abrahams BF, Babarao R, Dharma AD, Hudson TA, Maynard-Casely HE, and Robson R
- Abstract
The structure of Li(inox)⋅2/3 DMF (inox(-) =the N-oxide of the isonicotinate anion) consists of a 3D framework with solvent-filled, square cross-section channels of approximate dimensions 5.5×5.5 Å. Unfortunately, the Li(inox) framework is unstable upon removal of DMF from the channels. When the structurally related 4-hydroxybenzoic acid (H2 hba) was used in place of Hinox, and Zn(2+) in place of the Li(+) , a structurally similar but more robust network, Zn(hba), was obtained; the isostructural compound, Co(hba), may also be prepared. Longer ligands with phenolate and carboxylate functional groups at opposite ends, such as the dianions of 4-coumaric acid (H2 cma) and 4'-hydroxy-4-biphenylcarboxylic acid (H2 hbpc), in combination with Zn(2+) yield Zn(cma) and Zn(hbpc) frameworks, respectively, with the same PtS topology but with larger channels. The coordination polymers remain intact after desolvation and exhibit microporosity, showing the ability to sorb significant quantities of CO2 , CH4 , and H2 ., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2015
- Full Text
- View/download PDF
49. Tuning the cavities of zirconium-based MIL-140 frameworks to modulate CO2 adsorption.
- Author
-
Liang W, Babarao R, Church TL, and D'Alessandro DM
- Abstract
A combined experimental and computational study has revealed the interplay between the framework pore size and functionality on the CO2 adsorption performance of zirconium-based MIL-140 frameworks. The CO2-sorbent interactions were markedly influenced by pore-confinement effects which arise from the π-stacked arrangement of the ligands within the framework backbone.
- Published
- 2015
- Full Text
- View/download PDF
50. The first example of a zirconium-oxide based metal-organic framework constructed from monocarboxylate ligands.
- Author
-
Liang W, Babarao R, Murphy MJ, and D'Alessandro DM
- Abstract
This work reports the first example of a Zr-based MOF which is exclusively constructed from the monocarboxylate ligand formate. Despite the low surface area, the new material exhibits an unexpectedly favourable affinity for carbon dioxide over nitrogen at room temperature.
- Published
- 2015
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.