Intrinsic adsorption properties of CO2 on 5A and 13X zeolite

Data for the adsorption of CO₂ on 5A (CaA) and 13X (NaX) zeolite are critically evaluated. In addition, fresh data for the adsorption of CO₂ on 13X zeolite is reported. Three intrinsic properties are examined: q _max , the saturation loading, K _H , the Henry constant, and (?ΔH) _q , the isosteric heat of sorption. Below a reduced temperature T _r , of 0.9, the q _max values for both 5A and 13X zeolites are similar to theoretical values that may be derived using zeolitic crystallographic properties and the sorbate density calculated using the Rackett equation. For the region 0.9 ≤ Tr ≤ 1.0, the calculated q _max values exceed the theoretical values similarly calculated, indicating that the molecules have a smaller molar volume than in a similar liquid phase. This is a similar result to that observed in ionic liquids. Linear regressed equations are derived for q _max for the region 0.9 ≤ Tr ≤ 1.25. The Henry constant values for 5A are remarkably consistent for the five studies examined, with a correlation coefficient, R, of 0.999 for the van’t Hoff equation, but for the seven studies examined in 13X the data is more disperse as indicated by a correlation coefficient R of 0.899 for the van’t Hoff equation. The values of (?ΔH) _q , the isosteric heat of sorption are in agreement with the literature. An explanation is advanced for the discrepancy between the higher heats of sorption values obtained calorimetrically from those obtained from isosteric adsorption studies. Finally, the fresh data is observed to fit the Toth model with regression coefficients of 0.999. However, the parameters obtained for the Toth equation by regression are significantly different from the intrinsic properties derived earlier, indicating the difficulty of deriving intrinsic parameters from isotherm fits.     

Development of a Novel Electrochemical Biosensor for Detection and Discrimination of DNA Sequence and Single Base Mutation in dsDNA Samples Based on PNA‐dsDNA Hybridization – a new Platform Technology

In spite of the extensive attention paid on the development of various DNA detection strategies, very few studies have been reported regarding direct detection of DNA sequence and mutation in dsDNA. Here, we describe the feasibility of detection and discrimination of target DNA sequences and single base mutations (SBM) directly in double‐stranded oligonucleotides and PCR products without the need for denaturation of the target dsDNA samples. This goal was achieved by employing a peptide nucleic acid (PNA) chain, self‐assembled on the gold electrode as a probe, which binds to dsDNA and forms PNA‐dsDNA hybrid.     

Seeing the Unseen: Experimental Observation of Magnetic Anapole State Inside a High-Index Dielectric Particle

The existence of non-radiating electromagnetic sources attracts much attention in photonic community and gives rise to extensive discussions of various applications in lasing, medical imaging, sensing, and nonlinear optics. In this article, the existence of magnetic anapole states (or magnetic-type non-radiating sources) characterized by a suppressed magnetic dipole radiation in a dielectric cylindrical particle is theoretically predicted and experimentally demonstrated. The specific features of the magnetic anapole state under ideal conditions are identified, followed by a demonstration of how their existence can be detected in practical structures. The concept is valid in various frequency bands from visible range for nanoparticles to microwave range for millimeter size objects. The experimental study is performed in microwave frequency range which allows not only to measure the far-field (scattered field) characteristics, but also to probe the peculiar field profile directly inside the dielectric particle. The experimental results agree well with the analytical ones and pave the way to detect and identify nontrivial different-type anapole states.     

用于合成新型1,3,5-三芳基吡唑啉衍生物的磷钨酸铯盐的纳米塑形、模板合成及结构研究(英文)

The elimination of the silica matrix of composites by HF occurred by a two-step reaction deposition of a Cs2.5H0.5PW12O40(CsHPW) salt nanocrystal.We used 2D hexagonal SBA-15 silica as a template for the nanofabrication of CsHPW nanoparticles.Nanocast CsHPW materials are stable against leaching and colloidization in polar solvents.The catalytic performance of the nanocast CsHPW materi-als exceeded that of bulk Cs2.5H0.5PW12O40,which is the most active among the acidic HPW salts.A series of novel 1,3,5-triaryl-pyrazoline derivatives were synthesized by the reaction between chalcone and phenylhydrazine in high yield in the presence of CsHPW salt nanocrystals.     

Pencil Lead Electrode Modified with Hemoglobin Film as a Novel Biosensor for Nitrite Determination

In the present paper, the electrochemical reduction of nitrite at a hemoglobin modified pencil lead electrode (Hb/PLE) is described. The electrochemical properties of nitrite were studied by cyclic voltammetry and chronoamperometry. Results showed that the hemoglobin film has an excellent electrochemical activity towards the reduction of nitrite. By using voltammetric and chronoamperometric methods, α, n_α and n were calculated. Then the ability of the electrode for nitrite determination was investigated using differential pulse voltammetry. The electrocatalytic reduction peak currents were found to be linear with the nitrite concentration in the range from 10 to 220 µM with a detection limit of 5 µM. The relative standard deviation is 2 % for 3 successive determinations of a 100 µM nitrite solution. This modified electrode was successfully used for the detection of low amounts of NO₂^? in spinach sample and a spiked sample of tap water.     

Development of Voltammetric Sensor for Determination of Tryptophan Using MWCNTs‐modified Sol‐gel Electrode

In the present work, an electrochemical sensor was developed for simple and sensitive determination of tryptophan (Trp) using multi‐walled carbon nanotubes modified sol‐gel electrode (MWCNTs/SGE). The electrocatalytic oxidation of tryptophan was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that the oxidation peak current of Trp at the MWCNTs/SGE was greatly improved compared with that of the bare SGE. Furthermore, at the MWCNTs/SGE, the anodic peak potential of Trp is shifted about 220 mV to more negative value indicated that modified electrode has better electrocatalytic activity for electro‐oxidation of Trp. The anodic peak currents increased linearly with the concentration of tryptophan in the range of 0.2 × 10^?6 to 15 × 10^?6 M with a detection limit of 0.139 × 10^?6 M (at an S/N = 3).     

Role of droplet bridging on the stability of particle-containing immiscible polymer blends

The effect of micron-sized hydrophobic calcium carbonate particles on the stabilization of polydimethylsiloxane (PDMS)/polyisobutylene (PIB) immiscible model blends is investigated in this study. The analytical splitting of bulk and liquid–liquid interface contributions from the droplet bridging one is successfully performed due to the negligible contribution of hydrophobic microparticles to the bulk rheology of phases. The presence of particles at the fluid–fluid interface is supported by wetting parameter calculation and verified by optical microscopy observations. Moreover, direct visualizations shows that particles are able to form clusters of droplets by simultaneously adsorbing at two fluid–fluid interfaces and glue-dispersed droplets together, probably due to the patchy interactions induced by heterogeneous distribution of particles along the interface. Rheological studies show that the flow-induced coalescence is slowed down upon addition of particles and almost suppressed with the addition of 4 wt% particles. The linear viscoelastic response is modeled to estimate interfacial tension by considering the contribution of particle-induced droplet aggregation in addition to bulk and droplet deformation ones. From linear and nonlinear viscoelastic responses, the improved stability of filled polymer blends is attributed to the interfacial rheology and/or the bridged structure of droplets, even though the interfacial area is not fully covered by particles. Furthermore, Doi–Ohta scaling relations are investigated by employing stress growth response upon step-up of shear flow.     

Natural Convection Induced by a Heated Vertical Plate Embedded in a Porous Medium with Transpiration: Local Thermal Non-equilibrium Similarity Solutions

This paper is concerned with the thermal non-equilibrium free convection boundary layer, which is induced by a vertical heated plate embedded in a saturated porous medium. The effect of suction or injection on the free convection boundary layer is also studied. The plate is assumed to have a linear temperature distribution, which yields a boundary layer of constant thickness. On assuming Darcy flow, similarity solutions are obtained for governing the steady laminar boundary layer equations. The reduced Nusselt numbers for both the solid and fluid phases are calculated for a wide range of parameters, and compared with asymptotic analyses.