Purification on Kappa Carrageenan by Re-Precipitation Technique

Purification on kappa (ƙ) carrageenan was performed by dissolving ƙ-carrageenan powder in distilled water and re-precipitated with ethanol and n-hexane separately during re-precipitation process. The purified kappa carrageenan was analyzed by using Fourier transform infrared (FTIR) spectroscopy and carbon, hydrogen, nitrogen, and sulfur (CHNS) elemental analysis. The outcomes from FTIR showed there are physical changes due to intermolecular interactions which lead to decrease and lower intensity of hydroxyl band at 3345 cm-1 after re-precipitated with n-hexane, compared to re-precipitation with ethanol and unpurified ƙ-carrageenan. There were variations observed in the percentages of C, H and S in the CHNS analysis between unpurified and purified ƙ-carrageenan. The successfully purified ƙ-carrageenan are suitable to be used for further application.

Hydrothermal-to-metasomatic overprint of the neovolcanic rocks evidenced by composite apatite crystals: a case study from the Maglovec Hill, Slanské vrchy Mountains, Slovakia

The apatite assemblage from Maglovec hill (Slanské vrchy Mountains near the city of Prešov) from fissures of hydrothermally altered neovolcanic rocks (andesites and related lithologies) was studied. The assemblage consists of two different morphological apatite types (apatite in cores of prismatic crystals and fibrous apatite mantling these cores). The assemblage was investigated by a multi-analytical approach to reveal its unique chemical composition and structure. Both types of apatite display zoning visible in back-scattered electron (BSE) images. Core apatite is relatively homogenous with porous rims appearing darker in the BSE images at the contact with fibrous apatite, and occasionally with darker regions along fractures. These parts are depleted in trace elements, mostly in LREE. Fibrous apatites display concentric and/or patchy zoning. Dark regions in fibrous apatite occasionally display a porous structure. In part of fibrous crystals, substitution of (CO3)2− for phosphorus is confirmed by Raman spectroscopy by the presence of a band at ~ 1071 cm−1. This method also confirmed the presence of OH in different populations in the structure of all apatite types. The three most important observed peaks are caused by vibrations of hydroxyls influenced by different adjacent anions: hydroxyl (band at ~ 3575 cm−1); fluorine (band at ~ 3535–3540 cm−1); chlorine (band at ~ 3494 cm−1). In REE-depleted parts of both apatite types, fine inclusions of monazite and rarely Th-rich silicate are observed. The acquired data suggest a hydrothermal origin of this assemblage and indicate a formation sequence of distinct apatite types. Moreover, minerals from the epidote group were identified, which have not been described from this locality before as well as vanadium-rich magnetites that form exsolution lamellae in ilmenite grains.

Influence of the Type of Epoxy Resin and Concentration of Glycidylisobutyl-POSS in the Properties of Nanocomposites

Epoxy resin is one of the most used resins for obtaining composites and coatings. Its properties have been modified using many materials, mainly based on nanotechnology, such as clays and polyhedral oligomeric silsesquioxanes (POSS). POSS may increase thermal and mechanical resistance and hydrophobicity of the epoxy resin. This study aims at characterizing epoxy nanocomposites, using two distinct resins (DGEBA and DGEBF) and an addition of glycidylisobutyl-POSS in contents of 2.5% and 5% (w/w), through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Samples showed an amorphous halo due to the epoxy resin and a characteristic peak of POSS. TGA results showed a greater residual mass in DGEBF systems due to its wider formation of crosslinks. FTIR spectra demonstrated a higher amplitude of the hydroxyl band in DGEBF 5% system, which may affect its hydrophilic behavior because of the molecular mobility and resin weight reduction. DMA results showed that DGEBA systems are more flexible than DGEBF.

Modification of kaolinite by controlled hydrothermal deuteration – a DRIFT spectroscopic study

Kaolinites were modified by controlled hydrothermal deuteration. Both infrared and near infrared vibration spectra of deuterated kaolinite were investigated by Diffuse Reflectance Infrared Fourier Transform spectroscopy. The stretching vibrations (v) of deuteroxyl groups of the kaolinite were observed at 2726, 2709, 2697 and 2667 cm-1, respectively. The overtone bands (2n) of the deuteroxyl groups were visible in NIR regions at 5454, 5419, 5388 and 5342 cm-1, respectively. The lattice vibrations of the kaolinite taking part in deuteration included 937, 915, 792, 751 and 690 cm-1 which are assigned to hydroxyl group-related deformation or translation-vibration mode. The hydroxyl band at 3435 cm-1 with its deuteroxyl band at 2542 cm-1 resulted from unevenly distributed structural defects, either due to the isomorphous substitution of foreign cations or the imperfections of the kaolinite lattice structure.

Altitude profile of airglow hydroxyl emission

A rocket-borne cooled (S-1) filter photometer was flown from Resolute Bay, Northwest Territories 75° N during geomagnetically quiet conditions. The derived altitude profile of the (6–2) hydroxyl band emission shows a peak at 95 km. An airglow background of 2.7 R A−1 or less at 8380 A is reported for altitudes above 125 km.