Infrared ellipsometry of nanometric anisotropic dielectric layers on absorbing materials

An inversion problem of infrared ellipsometry is resolved on the basis of a fresh mathematical approach, which does not use the traditional regression analysis for data handling and has no need of initial guesses for the desired parameters. It is shown that obtained simple analytical equations for ellipsometric quantities open up new possibilities for determining optical parameters of an anisotropic ultrathin layer. The novel method possesses very high sensitivity because it is based on the phase conversion measurements of polarized reflected light. The method is tested using a numerical simulation and the results demonstrate clearly that it is successfully applicable for nanometric layers in the infrared spectral region.     

Different Species of Mercury in the Livers of Tropical Dolphins

Abstract

Four kinds of mercury species (inorganic mercury (Hg_inorg), methylmercury (MeHg), total organic mercury (ΣHg_org), and insoluble mercury, deemed to be mercuric selenide (HgSe), were determined in the livers of dolphins from the Brazilian coast. The MeHg was identified and quantified in the toluene layer on a Gas Chromatograph with an Electron Capture Detector (GC-ECD). The ΣHg_org was isolated by acid leaching (H₂SO₄-KBr-CuSO₄) and then extracted into CH₂Cl₂. The ΣHg_org and Hg_inorg were determined by Cold-Vapor Atomic Absorption Spectroscopy (CV-AAS). The MeHg was the smallest fraction of Hg_tot, with a median of 9%, whereas the highest fraction of the Hg_tot was as HgSe, corresponding to 53%. The fractions of Hg_inorg and ΣHg_org corresponded to 30% and 39%, respectively. The lowest fraction of MeHg and the highest fraction of HgSe in the liver of all animals are related to different capacities or strategies of detoxification of methylmercury in this organ.     

Pt(II) Complexes with Azolate‐containing Bidentate Chelate: Design,Photophysics, and Application

This review is aimed at the current research progression of a unique class of Pt(II ) metal complexes bearing at least one azolate‐containing bidentate chelate. The azole fragment can link to a neutral heteroaromatic entity or another azole and form bidentate chelates, such as monoanionic 3‐pyridyl‐1H ‐pyrazole and derivatives, dianionic 3,3′‐bi‐1H ‐pyrazole, 3,3′‐(1‐methylethylidene)‐bis‐1H ‐pyrazole, and their analogs. These azole‐containing chelates readily react with a variety of Pt(II) reagents to afford the corresponding bis‐bidentate Pt(II) complexes. Most of them were highly emissive in solution, doped polymer matrix, thin film, and even as crystal or powder, due to the high ligand field strength exerted by these chelates and their high propensity in forming the singular square‐planar architecture and intermolecular aggregates with substantially strengthened Pt⋯Pt interaction, according to their structural design. Therefore, they hold bright prospects in academic research and future optoelectronic applications such as organic light‐emitting diodes.     

Electrical relaxation studies of olivine type nanocrystalline LiMPO4 (M=Ni,Mn and Co) materials

The olivine type LiMPO₄ (M=Ni, Mn and Co) materials were synthesized by solution combustion technique using glycine as fuel. The structural characterizations were explored to confirm the phase formation of materials. The scanning electron microscope was used to identify the morphology of olivine materials. The local structure and chemical bonding between MO₆ octahedral and (PO₄)^3- tetrahedral groups were probed by Raman spectroscopy. Grain and grain boundaries were contributed for ion relaxation and dc conduction in olivine materials. Two orders of enhancement in ionic conductivity was observed in these olivine materials than the reported value. Among all the explored olivine samples, LiMnPO₄ showed highest enhancement in conductivity due to weak Li–O bonding and largest unit cell volume.     

Silver-coated LiVPO4F composite with improved electrochemical performance as cathode material for lithium-ion batteries

Nano-structured LiVPO₄F/Ag composite cathode material has been successfully synthesized via a sol–gel route. The structural and physical properties, as well as the electrochemical performance of the material are compared with those of the pristine LiVPO₄F. X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveal that Ag particles are uniformly dispersed on the surface of LiVPO₄F without destroying the crystal structure of the bulk material. An analysis of the electrochemical measurements show that the Ag-modified LiVPO₄F material exhibits high discharge capacity, good cycle performance (108.5 mAh g⁻¹ after 50th cycles at 0.1 C, 93% of initial discharge capacity) and excellent rate behavior (81.8 mAh g⁻¹ for initial discharge capacity at 5 C). The electrochemical impedance spectroscopy (EIS) results reveal that the adding of Ag decreases the charge-transfer resistance (R_ct) of LiVPO₄F cathode. This study demonstrates that Ag-coating is a promising way to improve the electrochemical performance of the pristine LiVPO₄F for lithium-ion batteries cathode material.     

Study of Microwave Irradiation Polymerization in the Presence of Different Carriers

ABSTRACT

The influence of the presence of an inorganic carrier in the polymerization systems was investigated in this paper. Ten polymerization systems that contained different inorganic carriers such as Al₂O₃, SiO₂ were studied. The ten polymerization systems are dibutyltin Maleate (DBTM) and allyl thiourea (AT), DBTM and stearic acid vinyl ester (SAVE), SAVE and maleic anhydride (MH), SAVE and acrylamide (AM), itaconic acid (IA) and AM, SAVE and IA, AM and MH, IA, sodium acrylate (AANa), AM. It was found that the activity of monomer can be changed in the presence of a carrier and furthermore, the different species of carrier influence the activity of same monomer differently in the polymerization.     

Synthesis and properties of a newly obtained sorbent based on silica gel coated with a polyaniline film as the stationary phase for non-suppressed ion chromatography

The new sorbent for non-suppressed ion chromatography based on silica gel coated with a film of polyaniline (PANI) was obtained in a process of in situ polymerization of aniline by oxidation with ammonium peroxydisulfate. Raman analyses performed using a Thermo Scientific DXR confocal Raman Microscope equipped with the Omnic 8 software from Thermo Fisher Scientific have proved a uniform distribution of PANI on the surface of chromatographic beads and in the pores of the particle.     

Effects of Inorganic Salts on Micellization and Solubilization in an Aqueous Solution of Poly(ethylene oxide)/Poly(propylene oxide)/Poly(ethylene oxide) Triblock Copolymer

The effects of inorganic salts on micellization and solubilization of prednisolone in aqueous solution of poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymer (Pluronic P85) were studied. The effect of inorganic salts on decrease in the cloud point and the critical micelle concentration (cmc) of Pluronic P85 was the order of Na₂HPO₄ > NaH₂PO₄ > NaCl > NaBr. Moreover, it was found that Pluronic P85 forms two kinds of micelles: monomolecular micelles and polymolecular micelles. The polymolecular micelle increased with increasing amount of added inorganic salts. Moreover, solubilization behavior is explained from the standpoint of salting out for prednisolone and association characteristics of Pluronic P85.     

Soft microswimmers: Material capabilities and biomedical applications

In the last decades, microrobotics has attracted much attention of researchers due to the unique characteristics of shapes, propulsion mechanisms, and potential applications in the biomedical field. Recently, the research of microrobots has shifted to soft microrobots owing to their softness, elasticity and reconfigurability benefiting to interact with the complex channels in the human body compared to their rigid counterparts. There is significant progress on soft microswimmers and that encourages us to review this field timely to promote the development. In this review, we mainly highlight the progress of the soft microswimmers in recent years. The materials with softness, deformability and shape-morphing characteristics are surveyed as well as biocompatibility, followed by standard fabrication methods. Additionally, the locomotion based on self-propelled and external-field-driven mechanisms has been compared and discussed. Finally, the biomedical applications in imaging, targeted drug delivery and therapy, and microsurgery are highlighted followed by addressing the perspectives.     

Applications of single-drop microextraction in analytical chemistry: A review

Single-drop microextraction (SDME) has been recognized as one of the simple miniaturized sample preparation tools for the isolation and preconcentration of several analytes from a complex sample matrix. In this review, we explored the applications of SDME coupled with various analytical techniques (spectroscopy, chromatography, and mass spectrometry) for the analysis of organic molecules, inorganic ions, and biomolecules from various sample matrices including food, environmental, clinical, pharmaceutical, and industrial samples. Also, it summarizes the use of nanoparticles in SDME combined with various analytical tools for the rapid analysis of several trace-level target analytes. An overview of ionic liquids, deep eutectic solvents, and SUPRAS, which improved the selectivity and sensitivity of various analytical techniques toward several analytes, as promising extracting solvent systems in SDME is also included. Finally, discussed the impressive analytical features and future perspectives of SDME in this review article.