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Astaxanthin (ASTX) is a keto carotenoid, which possesses a non-polar linear central conjugated chain and polar β-ionone rings with ketone and hydroxyl groups at the extreme ends. It is well known as a super anti-oxidant, and recent clinical studies have established its nutritional benefits. Although it occurs in several forms, including free molecule, crystalline, aggregates and various geometrical isomers, in nature it exists primarily in the form of esters. Marine animals accumulate ASTX from primary sources such as algae. Nordic shrimps (P. borealis), which are harvested widely in the Atlantic Ocean, form a major source of astaxanthin esters. “Astaxanthin-rich shrimp oil” was developed as a novel product in a shrimp processing plant in Eastern Canada. A compositional analysis of the shrimp oil was performed, with a view to possibly use it as a nutraceutical product for humans and animals. Astaxanthin-rich shrimp oil contains 50% MUFAs and 22% PUFAs, of which 20% are omega-3. In addition, the shrimp oil contains interesting amounts of EPA and DHA, with 10%/w and 8%/w, respectively. Astaxanthin concentrations varied between 400 and 1000 ppm, depending on the harvesting season of the shrimp. Astaxanthin and its esters were isolated from the oil and analysed by NMR, FTIR and Micro-Raman spectroscopy. Astaxanthin mono- and diesters were synthesized and used as standards for the analysis of astaxanthin-rich shrimp oil. NMR and vibrational spectroscopy techniques were successfully used for the rapid characterization of monoesters and diesters of astaxanthin. Raman spectroscopy provided important intermolecular interactions present in the esterified forms of astaxanthin molecules. Also discussed in this paper is the use of NMR, FTIR and Micro-Raman spectroscopy for the detection of astaxanthin esters in shrimp oil. [ABSTRACT FROM AUTHOR]

Recent developments in the synthesis of transition metal oxides in the form of porous thin films have opened up opportunities in the construction of electrochromic devices with enhanced properties. In this paper, synthesis, characterization and electrochromic applications of porousWO3 thin films with different nanocrystalline phases, such as hexagonal,monoclinic, and orthorhombic, are presented. Asymmetric electrochromic devices have been constructed based on these porousWO3 thin films. XRD measurements of the intercalation/deintercalation of Li+ into/from the WO3 layer of the device as a function of applied coloration/bleaching voltages show systematic changes in the lattice parameters associated with structural phase transitions in LixWO3. Micro- Raman studies show systematic crystalline phase changes in the spectra of WO3 layers during Li+ ion intercalation and deintercalation, which agree with the XRD data. These devices exhibit interesting optical modulation (up to ∼70%) due to intercalation/deintercalation of Li ions into/from the WO3 layer of the devices as a function of applied coloration/bleaching voltages. The obtained optical modulation of the electrochromic devices indicates that, they are suitable for applications in electrochromic smart windows. [ABSTRACT FROM AUTHOR]

Domoic acid (DA) is a water-soluble marine neurotoxin produced and released by certain species of the diatom genus Pseudo-nitzschia. Present in coastal waters, it can be a threat to public health and marine life, and can result in severe economic losses to the molluscan shellfish and crustacean harvesting industries. Here we report on the efficiency of nanocrystalline (NC) titania (TiO2) thin films used as a photocatalyst in the ultraviolet light photodegradation of DA. Titanium dioxide thin films produced by a sol-gel dip-coating method in the presence of polyethylene glycol of different molecular weights (200, 400 and 600) were deposited on glass substrates and crystallised at 90°C. The films were characterised using spectroscopic ellipsometry, Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The photocatalytic activity measurements were carried out by immersing the NC TiO2 films in a DA solution (2500 ng ml-1) and then exposing them for various times at room temperature to UVA irradiation (λ = approximately 350 nm). The degradation of DA, quantified by HPLC analysis, was not significant when using daylight or ultraviolet light irradiation alone, whereas the NC TiO2 films prepared at low temperature proved to be a very efficient photocatalyst when used in conjunction with UVA light. The effectiveness of the photodegradation was improved by increasing molecular weight of polyethylene glycol, which increased the thickness of the film. The presence, transformation and degradation of three DA isomers were observed. The approach may eventually be practical for destroying DA in seawater used by aquaculture industry depuration facilities. [ABSTRACT FROM AUTHOR]

Abstract: Tungsten oxide (WO3) is one of the most promising materials for electrochromic devices and is currently investigated for applications in catalysis, ferroelectricity and in sensor technology. Here a molecular assembly approach to synthesize by sol–gel meso and macroporous thin films of tungsten oxide using polyethylene-glycol as a templating agent is reported. Micro-Raman spectroscopy has been employed to investigate the structure of WO3 thin films, deposited by dip-coating on glass, as a function of thermal annealing. This modified sol–gel route promotes the coexistence of a sub-stoichiometric monoclinic phase (most probably the WO2.72 phase) together with some hydrous phases (WO3·nH2O) even in samples heat treated up to 500 °C. [Copyright &y& Elsevier]

Abstract: Domoic acid (DA) is a water-soluble marine neurotoxin produced and released by Pseudo-nitzschia species. It is remarkably pervasive in North American coastal waters, where it is a threat to public health and some marine life, and has resulted in severe economic losses in the shellfish and crustacean harvesting industry. In this paper we report on the development of nanocrystalline titania thin films that were used as photocatalyst in the UV photodegradation of DA. TiO2 thin films produced by a sol–gel dip-coating method in the presence of polyethylene glycol (PEG) of different molecular weights (200, 400 and 600), were deposited on glass and fused quartz substrates, and crystallized at different temperatures (90, 500 and 900°C). The films were characterized using UV–vis, FTIR, SEM, XRD, and Raman spectroscopy. For the photocatalytic activity measurements, the TiO2 films were immersed in a DA solution (2500ng/mL) and exposed for various times at room temperature to UV irradiation (λ ∼350nm). DA analysis was carried out by HPLC, and the photocatalytic activity was quantified as the rate of disappearance of DA. The photocatalytic activity of the TiO2 thin films was studied as a function of their crystallization temperature, type of PEG content, and thickness. The films prepared at low temperature proved to be very efficient photocatalysts. They showed a higher photocatalytic activity than those produced at high temperature. Also, using PEG of higher molecular weight in the TiO2 coating solutions increased the effectiveness of the degradation. When using UV irradiation alone, without photocatalyst, the degradation of DA was not significant. The presence, transformation, and degradation of various DA isomers were observed during the photodegradation process, and a photodegradation mechanism is proposed. [Copyright &y& Elsevier]

Abstract: Tungsten oxide (WO3) is one of the most promising materials for electrochromic devices. In this paper, we report on a simple route for the low temperature synthesis of nanocrystalline WO3 films involving treatment of tungsten hexachloride and non-ionic tri-block copolymer surfactant at 100°C. The films were studied by Raman spectroscopy and transmission electron microscopy (TEM) for their structural properties and also by scanning electron microscopy (SEM) to understand it’s microstructure. Raman studies show the presence of different nanocrystalline phases (m-WO3, and WO3 ·1/3 H2O) embedded in an amorphous matrix. A TEM diffraction pattern shows the nanocrystalline nature and a preferred growth direction for the crystallites. An electrochromic system using the low temperature WO3 film as an active electrode was fabricated and tested. [Copyright &y& Elsevier]

Brookite-rich titanium dioxide films have been prepared for the first time by a sol–gel method by using together diethanolamine (DEA) and polyethylene glycol (PEG) as modulators. The brookite phase was found preponderant only in films heated slowly to 600 °C when some of the crystals grow large enough to form and stabilize this phase. The weight fraction of brookite in the crystalline phase was found by the analysis of XRD data to be around 70%. The presence of an important amount of brookite in the annealed TiO2 coating was also confirmed by the strong feature at 150 cm-1 in the Raman spectrum. The results obtained in this work confirm the strong dependence of the phase stability on the size of the crystallites. [Copyright &y& Elsevier]

TiO2 nanocrystalline thin films with varying degree of porosity have been prepared using a low temperature method. TiO2 films of the anatase form have been obtained by using a polyethylene glycol (PEG) modified sol-gel method. Densification and crystallization of the films was found to result from the thermal treatment of the dip coated films in boiling water. The films have been characterized by Raman, XRD, FTIR, AFM and optical methods. Highly transparent films with transmission in excess of 85% and porosity as high as 58% are formed predominantly of anatase crystallites of dimensions of the order of 5 nm. Initial results on lithium intercalation into these films resulting in an efficient optical modulation in the visible and near infrared regions demonstrate a good potential of these films for electrochromic applications. [ABSTRACT FROM AUTHOR]

The paper describes technology and principal results concerning the studies of hybrid photovoltaic devices possessing layers of ZnO nanocrystals with different sizes. The presented studies have shown that better photovoltaic efficiency is achieved for the ZnO nanocrystals with smaller sizes. The physical origin of the observed effects is observed. [ABSTRACT FROM AUTHOR]

Abstract: Mesoporous vanadium pentoxide (V2O5) films have been synthesized by hydrolysis of vanadium tri-isopropoxide (VO(OC3H7)3) in the presence of polyethylene glycol (PEG) as a structure-directing agent. The structure, the stoichiometry and the morphology of the films have been studied as a function of the thermal annealing by X-ray diffraction (XRD), micro-Raman spectroscopy, optical microscopy, scanning electron microscopy and atomic force microscopy. XRD patterns and Raman spectra show the presence of two previously unreported crystalline phases. The PEG:V2O5 molar ratio affects the temperature of phase formation, the amount and even the order in which the phases appear. The morphological characterization underlines the role of the surfactant to promote porous networks, formed by micrometric clusters of controlled shapes and patterns embedded in a homogeneous host matrix. [Copyright &y& Elsevier]

Abstract: Tungsten oxide (WO3) is one of the most promising materials for electrochromic devices. WO3 thin films have been prepared at low temperature by using a polyethylene glycol (PEG) assisted sol–gel method. The structure and the stoichiometry of films deposited by dip coating on glass substrates have been studied as a function of thermal annealing by XRD, FTIR and μ-Raman. PEG-containing samples show improved electrochromic efficiency due to the formation of sub-stoichiometric, nanocrystalline phases. The electrochromic performance of WO3 films gets worse for annealing temperatures higher than 300°C due to massive Na absorption from the substrate. [Copyright &y& Elsevier]