The Change in Antioxidant Properties of Dextran‐Coated Redox Active Nanoparticles Due to Synergetic Photoreduction–Oxidation

Nanoparticles have proven to be novel material with resourceful applications in the field of nanomedicine. Cerium oxide nanoparticles (CNPs) coated with dextran (Dex–CNPs) have been shown to exhibit anticancer properties which is attributed to the change in oxidation states mediated at the oxygen vacancies on the surface of CNPs. In this study, the extreme sensitivity of Dex–CNPs to visible light is demonstrated using room light with a clear indication of synergetic phenomenon of photoreduction of CNPs in the presence of dextran which undergoes simultaneous oxidation. The phenomenon was further confirmed through a systematic time‐based expedited study using a high intensity visible light source. The physiochemical changes of Dex–CNPs such as dispersion stability, pH, surface chemistry, antioxidant property, cytotoxicity and the surrounding microenvironment of Dex–CNPs were significantly altered on exposure to visible light, thereby affecting the biological response. Given the significance of nanoparticles which are widely researched nanomaterials, in different fields of nanotechnology and biomedicine, this study demonstrates the significant changes in physiochemical properties of Dex–CNPs with light. The photoreduction of Dex–CNPs affects its bifunctional applications in cancer therapy and thereby this study puts forward the necessity to preserve and sustain their properties through proper storage.     

Vapor Phase Synthesis of SnS Facilitated by Ligand-Driven “Launch Vehicle” Effect in Tin Precursors

Extraordinary low-temperature vapor-phase synthesis of SnS thin films from single molecular precursors is attractive over conventional high-temperature solid-state methods. Molecular-level processing of functional materials is accompanied by several intrinsic advantages such as precise control over stoichiometry, phase selective synthesis, and uniform substrate coverage. We report here on the synthesis of a new heteroleptic molecular precursor containing (i) a thiolate ligand forming a direct Sn-S bond, and (ii) a chelating O^N^N-donor ligand introducing a “launch vehicle”-effect into the synthesized compound, thus remarkably increasing its volatility. The newly synthesized tin compound [Sn(SBu^t)(tfb-dmeda)] 1 was characterized by single-crystal X-ray diffraction analysis that verified the desired Sn:S ratio in the molecule, which was demonstrated in the direct conversion of the molecular complex into SnS thin films. The multi-nuclei (¹H, ¹³C, ¹⁹F, and ¹¹⁹Sn) and variable-temperature 1D and 2D NMR studies indicate retention of the overall solid-state structure of 1 in the solution and suggest the presence of a dynamic conformational equilibrium. The fragmentation behavior of 1 was analyzed by mass spectrometry and compared with those of homoleptic tin tertiary butyl thiolates [Sn(SBu^t)₂] and [Sn(SBu^t)₄]. The precursor 1 was then used to deposit SnS thin films on different substrates (FTO, Mo-coated soda-lime glass) by CVD and film growth rates at different temperatures (300–450 °C) and times (15–60 min), film thickness, crystalline quality, and surface morphology were investigated.     

The Role of Phase Migration of Carbon Nanotubes in Melt-Mixed PVDF/PE Polymer Blends for High Conductivity and EMI Shielding Applications

In this work, the effects of blend ratio and mixing time on the migration of multi-walled carbon nanotubes (MWCNTs) within poly(vinylidene fluoride) (PVDF)/polyethylene (PE) blends are studied. A novel two-step mixing approach was used to pre-localize MWCNTs within the PE phase, and subsequently allow them to migrate into the thermodynamically favored PVDF phase. Light microscopy images confirm that MWCNTs migrate from PE to PVDF, and transmission electron microscopy (TEM) images show individual MWCNTs migrating fully into PVDF, while agglomerates remained trapped at the PVDF/PE interface. PVDF:PE 50:50 and 20:80 polymer blend nanocomposites with 2 vol% MWCNTs exhibit exceptional electromagnetic interference shielding effectiveness (EMI SE) at 10 min of mixing (13 and 16 dB, respectively-at a thickness of 0.45 mm), when compared to 30 s of mixing (11 and 12 dB, respectively), suggesting the formation of more interconnected MWCNT networks over time. TEM images show that these improved microstructures are concentrated on the PE side of the PVDF/PE interface. A modified version of the “Slim-Fast-Mechanism” is proposed to explain the migration behavior of MWCNTs within the PVDF/PE blend. In this theory, MWCNTs approaching perpendicular to the interface penetrate the PVDF/PE interface, while those approaching in parallel or as MWCNT agglomerates remain trapped. Trapped MWCNTs act as barriers to additional MWCNTs, regardless of geometry. This mechanism is verified via TEM and scanning electron microscopy and suggests the feasibility of localizing MWCNTs at the interface of PVDF/PE blends.     

Interplay of Anion-π+ and π+-π+ Interactions in Novel Pyrido[2,1-a]isoquinolinium-Based AIEgens - Substituent- and Counterion-Dependent Fluorescence Modulation and Applications in Live Cell Mitochondrial Imaging**

Recently, the concept of anion-π⁺ interactions has witnessed unique applications in the field of AIEgen development. In this contribution, we disclose a consolidated study of a library of N-doped ionic AIEgens accessed through silver-mediated cyclization of pyridino-alkynes. A thorough photophysical, computational and crystallographic study has been conducted to rationalize the observed substituent- and counterion-dependent fluorescence properties of these luminogens. We further elucidate the prominent role of anion-π⁺ interactions, π⁺-π⁺ interactions and other non-covalent interactions, in inhibiting the undesired ACQ effect. Finally, we have also demonstrated the application of selected AIEgens for imaging of mitochondria in live cells.     

External electric field induced modulation instability of an electromagnetic beam in two-photon photorefractive materials

The modulation instability of a broad electromagnetic beam in a biased two-photon photovoltaic photorefractive material, due to two-photon-photorefractive effect has been investigated. The one-dimensional modulation instability growth rate has been estimated under the linear stability framework. The behavior of the gain spectrum is different in low and high power regions. It has been predicted that, with the application of external electric field, it is possible to initiate and control growth of the instability in those media, where modulation instability was hitherto prohibited. The influence of different system parameters on the instability growth rate has been examined.     

Electrostatic analysis for designing of efficient discharge cell structures in AC plasma displays

The high luminous efficacy of plasma display demands high luminance at reduced discharge power. The discharge power can be reduced by several steps, one of them being reduction of gas breakdown voltage. In this paper, improved discharge cell structures are introduced that favor reduction of the gas breakdown voltage. The simulated electric field profiles for these structures indicate the low voltage requirement with increased electric field concentration in the discharge gap. The experimental measurements of breakdown voltage and discharge delay time in the test panels also support the simulation results. The important features of these discharge cell structures are discussed.     

A Facile Molecular Precursor‐based Synthesis of Ag2Se Nanoparticles and Its Composites with TiO2 for Enhanced Photocatalytic Activity

The reactions of different silver(I) reagents AgX (X^?=iodide, trifluoroacetate, triflate) with selenoethers R₂Se (R=Me, tBu) in a variety of solvents were investigated in relation with their use as precursors for Ag₂Se nanomaterials. Different reaction conditions led to different reactivities and afforded either molecular complexes or metal selenide nanoparticles. The reactions leading to in situ formation of the metal selenide nanoparticles were then extended in the presence of commercial TiO₂ (P25) to prepare silver selenide–titania nanocomposites with different Ag/Ti ratios. These nanocomposites, well characterized by elemental analysis (Ag, Se), PXRD, TEM, BET, XPS and UV/Vis studies, were investigated as photocatalysts for the degradation of formic acid (FA) solution. The xAg₂Se‐TiO₂ nanocomposites (x=0.01, 0.13 and 0.25 mol %) exhibited a much higher catalytic activity as compared to P25, which is an established benchmark for the photocatalysis under UV light, and retained a good photocatalytic stability after recycling for several times.     

Inhibitory Effect of Polyphenols from the Whole Green Jackfruit Flour against α-Glucosidase, α-Amylase,Aldose Reductase and Glycation at Multiple Stages and Their Interaction: Inhibition Kinetics and Molecular Simulations

For the first time, α-glucosidase, α-amylase, aldose reductase, and glycation at multiple stages inhibitory assays were used to explore the antidiabetic potential of whole unripe jackfruit (peel with pulp, flake, and seed). Two polyphenols (phenolic acids) with strong antihyperglycaemic activity were isolated from the methanol extract of whole jackfruit flour (MJ) using activity-guided repeated fractionation on a silica gel column chromatography. The bioactive compounds isolated were identified as 3-(3,4-Dihydroxyphenyl)-2-propenoic acid (caffeic acid: CA) and 4-Hydroxy-3,5-dimethoxybenzoic acid (syringic acid: SA) after various physicochemical and spectroscopic investigations. CA (IC₅₀: 8.0 and 26.90 µg/mL) and SA (IC₅₀: 7.5 and 25.25 µg/mL) were identified to inhibit α-glucosidase and α-amylase in a competitive manner with low Ki values. In vitro glycation experiments further revealed that MJ and its components inhibited each stage of protein glycation as well as the generation of intermediate chemicals. Furthermore, CA (IC₅₀: 3.10) and SA (IC₅₀: 3.0 µg/mL) inhibited aldose reductase effectively in a non-competitive manner, respectively. The binding affinity of these substances towards the enzymes examined has been proposed by molecular docking and molecular dynamics simulation studies, which may explain their inhibitory activities. The found potential of MJ in antihyperglycaemic activity via inhibition of α-glucosidase and in antidiabetic action via inhibition of the polyol pathway and protein glycation is more likely to be related to the presence of the phenolic compounds, according to our findings.     

Effect of Pr-filling in binary skutterudites CoX3 (P,As and Sb) on structural,electronic, elastic and transport properties

ABSTRACT

We have studied the effect on the structural, electronic, elastic and transport properties of binary skutterudite CoX₃ (X?=?P, As, Sb) after filling void spaces by Pr atoms. All the calculations are carried out using the full-potential linearised augmented plane wave (FP-LAPW) method within the generalised gradient approximation (GGA) viz, PBE, and PBEsol. In case of binary skutterudites, equilibrium lattice parameters obtained using PBEsol functional are in good agreement with the theoretical and experimental results. The Hubbard parameter (U) has been used with PBEsol-GGA functional to see its effect on the band structures of binary and ternary compounds. Filling of Pr atoms at void positions in binary skutterudites creates the gap between the valence and conduction band. The obtained values of the elastic constants show that CoX₃, PrCo₄X₁₂ (X?=?P, As, Sb) are mechanically stable and brittle. Mechanically, PrCo₄P₁₂ and PrCo₄As₁₂ are anisotropic, but PrCo₄Sb₁₂ is isotropic. Obtained saturated Seeback coefficients are approximate ?60?μV/K (PrCo₄P₁₂), ?80?μV/K (PrCo₄As₁₂) and ?68?μV/K (PrCo₄Sb₁₂) in the spin-up channel while in the spin-down channel corresponding values are ?10, ?50 and ?120?μV/K at 800?K, respectively. These values are higher in magnitude than that in the corresponding binary compounds.