Modeling absorption spectrum and saturation intensity of ZnO nano-colloid

In this work, the complex magnitude of the dielectric constant of a thin film of ZnO nano-particles has been obtained in the range of visible spectrum. Using this spectrum, the UV–visible absorptive spectrum of ZnO spherical nano-colloid is obtained using Mie theory. The absorption spectrum of ZnO nano-colloid has been related to the optical properties of the prepared thin film with a simulation model based on the Mie theory and the findings are corroborated by fitting with the experimental results. Based on this curve fitting, the volume fraction of nanoparticles in the nano-colloid is obtained and the diameter (and the Bohr radius) of the molecules contributing in a nanoparticle crystal structure has been obtained. In this paper, frequency dependence of the optical properties coefficients and also local field considerations are applied. Finally the precise magnitude of saturation intensity of ZnO nano-colloid is measured.     

Metal organic framework–derived core-shell CuO@NiO nanosphares as hole transport material in perovskite solar cell

Journal of Solid State Electrochemistry - Cu-Ni bimetallic organic frameworks were synthesized by a facile and stepwise solvothermal method, utilizing metal organic framework as precursor....     

Thiourea-treated graphene aerogel as a highly selective gas sensor for sensing of trace level of ammonia

As a result of this study, a new and simple method was proposed for the fabrication of an ultra sensitive, robust and reversible ammonia gas sensor. The sensing mechanism was based upon the change in electrical resistance of a graphene aerogel as a result of sensor exposing to ammonia. Three-dimensional graphene hydrogel was first synthesized via hydrothermal method in the absence or presence of various amounts of thiourea. The obtained material was heated to obtain aerogel and then it was used as ammonia gas sensor. The materials obtained were characterized using different techniques such as Fourier transform infra red spectroscopy (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thiourea-treated graphene aerogel was more porous (389 m² g⁻¹) and thermally unstable and exhibited higher sensitivity, shorter response time and better selectivity toward ammonia gas, compared to the aerogel produced in the absence of thiourea. Thiourea amount, involved in the hydrogel synthesis step, was found to be highly effective factor in the sensing properties of finally obtained aerogel. The sensor response time to ammonia was short (100 s) and completely reversible (recovery time of about 500 s) in ambient temperature. The sensor response to ammonia was linear between 0.02 and 85 ppm and its detection limit was found to be 10 ppb (3S/N).     

An assessment of theoretical procedures for π-conjugation stabilisation energies in enones

We introduce a representative database of 22 α,β- to β,γ-enecarbonyl isomerisation energies (to be known as the EIE22 data-set). Accurate reaction energies are obtained at the complete basis-set limit CCSD(T) level by means of the high-level W1-F12 thermochemical protocol. The isomerisation reactions involve a migration of one double bond that breaks the conjugated π-system. The considered enecarbonyls involve a range of common functional groups (e.g., Me, NH₂, OMe, F, and CN). Apart from π-conjugation effects, the chemical environments are largely conserved on the two sides of the reactions and therefore the EIE22 data-set allows us to assess the performance of a variety of density functional theory (DFT) procedures for the calculation of π-conjugation stabilisation energies in enecarbonyls. We find that, with few exceptions (M05-2X, M06-2X, BMK, and BH&;HLYP), all the conventional DFT procedures attain root mean square deviations (RMSDs) between 5.0 and 11.7 kJ mol^?1. The range-separated and double-hybrid DFT procedures, on the other hand, show good performance with RMSDs below the ‘chemical accuracy’ threshold. We also examine the performance of composite and standard ab initio procedures. Of these, SCS-MP2 offers the best performance-to-computational cost ratio with an RMSD of 0.8 kJ mol^?1.     

Synthesis,tautomeric stability,spectroscopy and computational study of a potential molecular switch of (Z)-4-(phenylamino)pent-3-en-2-one

The (Z)-4-(phenylamino) pent-3-en-2-one (PAPO) was synthesised applying carbon-based solid acid and described by experimental techniques. Calculated results reveal that its keto-amine form is more stable than its enol-imine form. A relaxed potential energy surface scan has been accomplished based on the optimised geometry of NH tautomeric form to depict the potential energy barrier related to intramolecular proton transfer. The spectroscopic results and theoretical calculations demonstrate that the intramolecular hydrogen bonding strength of PAPO is stronger than that in 4-amino-3-penten-2-one)APO(. In addition, molecular electrostatic potential, total and partial density of stats (TDOS, PDOS) and non-linear optical properties of the compound were studied using same theoretical calculations. Our calculations show that the title molecule has the potential to be used as molecular switch.     

Tuning the Size and Geometry of Heteroleptic Coordination Cages by Varying the Ligand Bent Angle

Spherical assemblies of the type [Pd_nL_2n]²ⁿ⁺ can be obtained from Pd^II salts and curved N-donor ligands, L. It is well established that the bent angle, α, of the ligand is a decisive factor in the self-assembly process, with larger angles leading to complexes with a higher nuclearity, n. Herein, we report heteroleptic coordination cages of the type [Pd_nL_nL′_n]²ⁿ⁺, for which a similar correlation between the ligand bent angle and the nuclearity is observed. Tetranuclear cages were obtained by combining [Pd(CH₃CN)₄](BF₄)₂ with 1,3-di(pyridin-3-yl)benzene and ligands featuring a bent angle of α=120°. The use of a dipyridyl ligand with α=149° led to the formation of a hexanuclear complex with a trigonal prismatic geometry; for linear ligands, octanuclear assemblies of the type [Pd₈L₈L′₈]¹⁶⁺ were obtained. The predictable formation of heteroleptic Pd^II cages from 1,3-di(pyridin-3-yl)benzene and different dipyridyl ligands is evidence that there are entire classes of heteroleptic cage structures that are privileged from a thermodynamic point of view.     

Optical properties of microphytobenthic biofilms (MPBOM): Biomass retrieval implication

Microphytobenthos Optical Model (MPBOM) provides the optical properties, absorption coefficient and refractive index, of a laboratory simulated microphytobenthic biofilm using the reflectance measurements derived from HySpex laboratory images, with the final aim of estimating photosynthetically active biomass. The high correlation between this biomass, expressed in chlorophyll a (mg Chl a m⁻²) and the absorption coefficient at the corresponding absorption wavelength of Chl a (673 nm) made possible the estimation of biomass for any absorption coefficient calculated from reflectance measurements of any other data set. The latter was validated for an independent data set which performed an acceptable estimation of biomass in comparison with the biomass measured by HPLC (R²=0.93). Finally, this model is designed to be applied to hyperspectral images, like airborne or satellite, in order to map biomass in the field.     

Anti-icing performance of superhydrophobic surfaces

This article studies the anti-ice performance of several micro/nano-rough hydrophobic coatings with different surface chemistry and topography. The coatings were prepared by spin-coating or dip coating and used organosilane, fluoropolymer or silicone rubber as a top layer. Artificially created glaze ice, similar to the naturally accreted one, was deposited on the nanostructured surfaces by spraying supercooled water microdroplets (average size ∼80 μm) in a wind tunnel at subzero temperature (−10 °C). The ice adhesion strength was evaluated by spinning the samples in a centrifuge at constantly increasing speed until ice delamination occurred. The results show that the anti-icing properties of the tested materials deteriorate, as their surface asperities seem to be gradually broken during icing/de-icing cycles. Therefore, the durability of anti-icing properties appears to be an important point for further research. It is also shown that the anti-icing efficiency of the tested superhydrophobic surfaces is significantly lower in a humid atmosphere, as water condensation both on top and between surface asperities takes place, leading to high values of ice adhesion strength. This implies that superhydrophobic surfaces may not always be ice-phobic in the presence of humidity, which can limit their wide use as anti-icing materials.     

An efficient method for synthesis of acylals from aldehydes using multi-walled carbon nanotubes functionalized with phosphonic acid(MWCNTs-C-PO_3H_2)

MWCNTs-C-PO_3H_2 has been used as an efficient,heterogeneous and reusable nanocatalyst for synthesis of acylals from aldehydes under solvent-free conditions at room temperature.A wide range of aldehydes was studied and corresponding products were obtained in good to excellent yields in short reaction times.Nanocatalyst can be easily recovered by centrifuge and reused for subsequent reactions for at least five times without deterioration in catalytic activity.The major advantages of the present method are high yields,short reaction time,recyclable catalyst and solvent-free reaction conditions at room temperature.