Tuning of Photonic band gap via combined effect of electric and optical fields in a blue phase liquid crystal composite

ABSTRACT

Blue phase liquid crystals are soft 3D photonic crystals in which the liquid crystal molecules self-assemble to form a cubic structure with lattice spacing of a few hundred nanometers resulting in selective reflection of colours in the visible spectrum. The corresponding wavelength or the ‘photonic band gap’ can be tuned using various external stimuli such as thermal, electric, magnetic and optical fields. Here, we report efficient tuning of photonic band gap by utilising the combination of electric and optical fields in a blue phase liquid crystalline system. The studies indicate that the chirality of the medium has a direct bearing on the direction of the wavelength shift and the extent of the photonic band gap tunability. More importantly, the synergistic effect of the two fields helps in reversible tuning of the band gap.     

Effectively promoted catalytic activity by adjusting calcination temperature of Ce-Fe-Ox catalyst for NH3-SCR

A series of Ce-Fe-O_x catalysts prepared by the different calcination temperatures (marked as CF-X, where X represented calcination temperature) were used to the selectivity catalytic reduction of NO_x by NH₃. The results explained the relationship between calcination temperature and the sulfate species over Ce-Fe-O_x, and then investigated the surface acidity and catalytic performance. The large amounts of sulfate species were formed over CF-450 and CF-550 while it was decomposed with further the increasing of calcination temperature, which resulted in the loss of surface acidity, causing a decrease in the catalytic activity over Ce-Fe-O_x. Thereby, the CF-450 catalyst showed the best catalytic activity and over 90% NO_x conversion was obtained at 244–450 °C. Besides, the favored pore structure, more Fe³⁺ active species, higher Ce³⁺ concentration and the abundance of chemical adsorbed oxygen species, as well as the surface acid sites, would together contribute to the excellent catalytic activity of CF-450 catalyst.     

Unveiling the binding interaction of zinc (II) complexes of homologous Schiff-base ligands on the surface of BSA protein: A combined experimental and theoretical approach

Four new zinc (II) complexes [Zn (HL¹H)Br₂] (1), [Zn (HL¹H)Cl₂] (2), [Zn₂(HL²)Br₃] (3), and [Zn (HL²)Cl] (4) have been synthesized by adopting template synthetic strategy and utilizing two homologous Schiff base ligands (H₂L¹ = 4-bromo-2-{[2-(2-hydroxyethylamino)-ethylimino]-methyl}-6-methoxyphenol, H₂L² = 4-bromo-2-{[3-(2-hydroxyethylamino)propylimino]methyl}-6-methoxyphenol), differing in one -CH₂- unit in the ligating backbone, by adopting template synthetic strategy. All the complexes have been characterized by single crystal X-ray diffraction analysis as well as by other routine physicochemical techniques. Ligand mediated structural variations have been observed and rationalized by density functional theoretical (DFT) calculations. Interaction of the complexes 1–4 with Bovine Serum Albumin protein (BSA) has been studied by different spectroscopic techniques. A complete thermodynamic profile (ΔH^o, ΔS^o and ΔG^o) was evaluated initially from the change in absorption and fluorescence spectra upon addition of BSA to the complexes. Appreciable binding constant values in the range ~ 0.94–4.51 × 10⁴ M⁻¹ indicate efficient binding tendency of the complexes to BSA with the sequence 1 ≅ 2 > 3 ≅ 4. Circular dichroism (CD), isothermal calorimetric titration experiments, molecular docking and molecular dynamics have been performed to gain deep insight into the binding regions of complex 1 to BSA. Experimental evidences suggest an interaction of zinc complexes at the surface of BSA protein and this particular binding has been exploited to determine unknown concentration of BSA protein. For this purpose complex 1 was explored as a BSA protein quantification tool.     

Efficient removal of As(V) from simulated arsenic-contaminated wastewater via a novel metal–organic framework material: Synthesis,structure, and response surface methodology

A novel metal–organic framework material {[N(C₂H₅)₃][Zn₂(ptmda)₂(μ₂-H₂O)]·(H₂O)_0.5}_n { GUT-3 ; H₂ptmda is 4,4′-([p-tolylazanediyl]bis [methylene])dibenzoic acid} was successfully synthesized using the hydrothermal method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. GUT-3 has a two-dimensional network based on dinuclear [Zn₂(ptmda)₂(μ₂-H₂O)]⁻ building units which formed an eightfold interpenetration network in GUT-3 molecules. Hirshfeld surface analysis revealed that H–H, C–H, and O–H bonds accounted for the majority of intermolecular interactions. Moreover, the interactions between GUT-3 and As(V) – the form of As(V) is AsO₄³⁻ – were analyzed in aqueous solutions in a batch system to study the effect of pH, concentration, adsorbent dose, adsorption time, adsorption temperature, and shaking speed. The kinetic and isotherm data of arsenic adsorption on GUT-3 were accurately modeled by pseudo-second-order, Langmuir (q_m = 33.91 mg/g), and Freundlich models. The Box–Behnken response surface method was used to optimize the adsorption conditions of As(V) from the simulated arsenic-contaminated wastewater. The effect of various experimental parameters and optimal experimental conditions was ascertained using the quadratic model.     

An insight into the potent antioxidant activity of a dithiocarbohydrazone appended cis-dioxidomolybdenum (VI) complexes

In search of antioxidants with enriched potency, the present study focus on the design and synthesis of a dithiocarbohydrazone, H₃TCL derived from thiocarbohydrazide and 3-ethoxysalicylaldehyde and its coordination complexes with molybdenum, viz, [MoO₂(HTCL)D] ( 1 – 2 ) (where D = methanol ( 1 ), DMSO ( 2 )) and [MoO₂(HTCL)D]·DMF (where D = H₂O ( 3 )). The synthesized compounds were characterised by elemental analysis, spectroscopic techniques (FT-IR, UV–vis and ¹H-NMR), conductivity measurements and cyclic voltammetry. Moreover the solid state structures of all the three complexes were established by single crystal X-ray diffraction analysis as mononuclear neutral species in which the molybdenum centre assumes a distorted octahedral geometry. The dithiocarbohydrazone binds to the molybdenum centre through its phenolate oxygen, O(1), azomethine nitrogen, N(1) and thioenolate sulfur, S(1) in a dianionic tridentate mode. The assessment of intermolecular contacts in the crystal arrangement was quantified using Hirshfeld surface analysis. Further the antioxidant potential of the dithiocarbohydrazone, H₃TCL and its molybdenum complexes 1 – 3 were evaluated using 1,1-diphenyl-2-picrylhydrazyl(DPPH), 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and total antioxidant assays. The antioxidant activities were then compared with standard antioxidant, L-ascorbic acid. The antioxidant potential of the synthesized compounds were then validated by molecular docking studies. Molecular modelling study was achieved to evaluate the recognition of target compound at the binding pocket of the human antioxidant enzyme, 3MNG. The docking results showed that the complexes selectively bond to the vital amino acids present in the binding pocket of the target enzyme, 3MNG.     

Detailed experimental and kinetic modeling study of 3-carene pyrolysis

3-Carene is an important potential biofuel with properties similar to the jet-propellant JP-10. Its thermal decomposition and combustion behavior is to date unknown, which is essential to assess its quality as a fuel. A combined experimental and kinetic modeling study has been conducted to understand the initial decomposition of 3-carene. The pyrolysis of 3-carene was investigated in a jet-stirred quartz reactor at atmospheric pressure, at temperatures varying from 650 to 1050 K, covering the complete conversion range. The decomposition of 3-carene was observed to start around 800 K, and it is almost complete at 970 K. Online gas chromatography shows that primarily aromatics are generated which suggests that 3-carene is not a good fuel candidate. The potential energy surface for the initial decomposition pathways determined by KinBot shows that a hydrogen elimination reaction dominates, giving primarily cara-2,4-diene. Next to this molecular pathway, radical pathways lead to aromatics via ring opening. The kinetic model was automatically generated with Genesys and consists of 2565 species and 9331 reactions. New quantum chemical calculations at the CBS-QB3 level of theory were needed to calculate rate coefficients and thermodynamic properties relevant for the primary decomposition of 3-carene. Both the conversion of 3-carene and the yields of the primary products (ie, benzene and hydrogen gas) are well predicted with this kinetic model. Rate of production analyses shows that the dominant pathways to convert 3-carene are hydrogen elimination reaction and radical chemistry.     

Calculated coupling constants 1J(X–Y) and 1K(X–Y), and fundamental relationships among the reduced coupling constants for molecules HmX–YHn,with X,Y ═ 1H, 7Li, 9Be, 11B, 13C, 15N, 17O, 19F, 31P, 33S,and 35Cl

Equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) calculations have been performed to determine coupling constants ¹J(X–Y) for 65 molecules H_mX–YH_n, with X,Y ═ ¹H, ⁷Li, ⁹Be, ¹¹B, ¹³C, ¹⁵N, ¹⁷O, ¹⁹F, ³¹P, ³³S, and ³⁵Cl. The computed ¹J(X–Y) values are in good agreement with available experimental data. The reduced coupling constants ¹K(X–Y) have been derived from ¹J(X–Y) by removing the dependence on the magnetogyric ratios of X and Y. Patterns are found for the reduced coupling constants on a ¹K(X–Y) surface that are related to the positions of X and Y in the periodic table.     

Slippery liquid-infused porous surface via thermally induced phase separation for enhanced corrosion protection

Slippery liquid-infused porous surface (SLIPS) is a rising star in corrosion protection owing to its outstanding corrosive medium resistance and self-healing property. The large-area and facile fabrication of SLIPS remains a challenge lying on the way of its practical application. Herein, we develop a novel SLIPS based on a porous polyvinylidene fluoride (PVDF) substrate fabricated by thermally induced phase separation. A sphere-packing structure can be easily obtained by blade-coating followed by cooling. The SLIPS exhibits an extremely low sliding angle of 5.8° so that it can resist the fouling of even the Chinese ink, ascribing to its slippery dynamic surface with low surface energy. We also evaluated the anti-corrosion performance of the SLIPS and superhydrophobic PVDF coating by electrochemical impedance spectroscopy (EIS) and scanning Kelvin probe technique (SKP), both of which exhibited enhanced corrosion resistance in 3.5 wt% NaCl solution due to the physical oil and air barriers against the corrosive medium penetration. Nevertheless, the SLIPS coatings performed outstanding self-healing properties because of the high fluidity of infused oil to recover the surface damages, and the self-healing process was recorded by the SKP.     

Improved Interfacial Bonding Strength and Reliability of Functionalized Graphene Oxide for Cement Reinforcement Applications

Poor bonding strength between nanomaterials and cement composites inevitably lead to the failure of reinforcement. Herein, a novel functionalization method for the fabrication of functionalized graphene oxide (FGO), which is capable of forming highly reliable covalent bonds with cement hydration products, and therefore, suitable for use as an efficient reinforcing agent for cement composites, is discussed. The bonding strength between cement and aggregates was improved more than 21 times with the reinforcement of FGO. The fabricated FGO also demonstrated many important features, including high reliability in cement pastes, good dispersibility, and efficient structural refinement of cement hydration products. With the incorporation of FGO, cement mortar samples demonstrated up to 40 % increased early and ultimate strength. Such results make the fast demolding and manufacture of light constructions become highly possible, and show strong advantages on improving productivity, saving cost, and reducing CO₂ emissions in practical applications.     

Strategies for the Controlled Covalent Double Functionalization of Graphene Oxide

Graphene oxide (GO) is a versatile platform with unique properties that have found broad applications in the biomedical field. Double functionalization is a key aspect in the design of multifunctional GO with combined imaging, targeting, and therapeutic properties. Compared to noncovalent functionalization, covalent strategies lead to GO conjugates with a higher stability in biological fluids. However, only a few double covalent functionalization approaches have been developed so far. The complexity of GO makes the derivatization of the oxygenated groups difficult to control. The combination of a nucleophilic epoxide ring opening with the derivatization of the hydroxyl groups through esterification or Williamson reaction was investigated. The conditions were selective and mild, thus preserving the structure of GO. Our strategy of double functionalization holds great potential for different applications in which the derivatization of GO with different molecules is needed, especially in the biomedical field.