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Compound Formation (compound + formation)
Selected AbstractsSolid-state compounds of stereoisomers: cis and trans isomers of 1,2-cyclohexanediol and 2,3-tetralindiolACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2007Michael A. Lloyd The phases of 1,2,3,4-tetrahydro-2,3-naphthalenediol (or 2,3-tetralindiol) and of 1,2-cyclohexanediol have been investigated. The structure of a very stable 1:1 compound (or co-crystal) of the cis and trans isomers of 2,3-tetralindiol, the existence of which has been known for nearly a century, has finally been determined. No evidence of any analogous compound between the cis and trans isomers of 1,2-cyclohexanediol has been found. The formation of solid-state compounds of stereoisomers is rare; it probably occurs only if the crystal packing of at least one of the isomers is unfavorable, e.g. if at least one of the melting points is lower than expected. Compound formation is usually unlikely because of the difficulty of simultaneously optimizing the translational spacings for both isomers, but that packing problem is avoided in the cis/trans compound of 2,3-tetralindiol because the two isomers are in very similar environments. In the structures of the individual 2,3-tetralindiol isomers there are clear conflicts between the competing packing requirements of the 1,2-diol moiety and the aromatic ring system; these conflicts are resolved better in the co-crystal than in the structures of the individual isomers. [source] Lipid damage during frozen storage of Gadiform species captured in different seasonsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 6 2007Santiago P. Aubourg Abstract Quality loss of two gadiform fish species (blue whiting, Micromesistius poutassou; hake, Merluccius merluccius) during frozen storage (,30 and ,10,°C; up to 12,months) was studied. For this, hydrolytic (formation of free fatty acids, FFA) and oxidative (conjugated dienes, peroxide and interaction compound formation) lipid damage were analysed. For both species, individual fishes captured in two different trials (May and November) were considered. Increasing (p,<0.05) lipid hydrolysis and oxidation (peroxide and interaction compound formation) were observed for all kinds of samples throughout the frozen storage. Interaction compound detection by fluorescence analysis showed the best correlation values with storage time. Some higher (p,<0.05) hydrolysis development could be observed in hake captured in May than in its counterpart from the November trial, while frozen blue whiting did not provide definite differences for FFA formation between both trials. Concerning peroxide formation, higher (p,<0.05) values were obtained for individual blue whiting and hake captured in November when compared to their corresponding May fish for both frozen storage conditions. Interaction compound formation was also found to be higher (p,<0.05) for November hake fish than for its counterpart captured in May, while blue whiting did not provide definite differences between trials. [source] Cyclic fatty acids in sunflower oils during frying of frozen foods with oil replenishment,EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2007Antonio Romero Abstract Frying of frozen foods has become popular because it considerably reduces cooking time. Polymers and cyclic fatty acid monomers (CFAM) formed during frying are potentially toxic and therefore their production should be minimized. Twenty discontinuous fryings of different frozen foods were carried out over ten consecutive days, in sunflower oil (SO) and in high-oleic acid sunflower oil (HOSO), by adding fresh oil after each frying to bring the volume of the fryer oil back to 3,L. CFAM methyl ester derivates were hydrogenated, isolated, concentrated and quantified by HPLC using a reverse-phase column, followed by gas chromatography. After 20,fryings, significantly higher contents of polar material, polymers and CFAM (all p,<0.001) were found in SO than in HOSO. Bicyclic compound formation was four times higher in SO (p,<0.001). The fat from the fried potatoes presented a polymer content very similar to that of their corresponding oils. The 100-g rations of the SO-fried potatoes from the 20th frying supply 49 or 15%, respectively, more polymers and CFAM and 1,mg more bicyclic fatty acids than the 100-g rations of HOSO-fried potatoes. Because digestion and absorption of polar material, polymers and CFAM occur, the data clearly show the advantageousness and advisability of frying with HOSO rather than SO. [source] Effect of oral hygiene instruction and scaling on oral malodour in a population of Turkish children with gingival inflammationINTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 6 2006C. KARA Summary. Aim., Oral malodour affects a large proportion of the population, and may cause a significant social or psychological handicap to those suffering from it. The condition has a positive correlation with the accumulation of bacterial plaque in the oral cavity. The aim of the present study was twofold: first, to determine whether oral malodour and periodontal disease parameters are associated with one another in 150 Turkish subjects (mean age ± SD = 9·1 ± 2·7 years; age range = 7,12 years); and secondly, to investigate the impact of oral hygiene instruction and scaling on oral malodour. Design., The parameters measured included whole-mouth odour judge scoring, halimeter measurements, saliva pH scores, gingival index, plaque index, and probing depth before and after the treatment procedures. Results., Odour judge scores were significantly associated with halimeter findings. However, gingival index, plaque index and probing depth were significantly associated with odour judge scores and halimeter scores. The statistical analysis revealed that periodontal treatments caused a significant reduction (P < 0·001) in volatile sulphur compound formation. Conclusion., These results suggest that, in the population studied, periodontal health and oral malodour are associated with one another. Oral malodour levels were significantly reduced after treating gingival inflammation. Thus, in order to avoid oral malodour in children, oral care should not be neglected. [source] Physically and chemically modified polycarbonate by metal ion implantationADVANCES IN POLYMER TECHNOLOGY, Issue 3 2008Rashi Nathawat Abstract Changes in physical and chemical properties have been studied for polycarbonate (PC) implanted by 100 keV Ni+ with various fluences from 1 × 1014 to 1 × 1016 ions/cm2. Changes in the surface morphology and composition have been observed with atomic force microscopy and X-ray diffraction (XRD). Ni particles as precipitates in PC were observed by cross-section transmission electron microscopy at the 100-nm depth. Ion implantation induces changes in the topography of PC as indicated by a dramatic increase in surface roughness with ion fluence. Implanted metal ions show direct evidence of compound formation on the surface. Chemical changes in the surface region have been observed by Raman spectroscopy and UV,vis spectroscopy. UV,vis absorption analysis indicates a drastic decline in optical band gap from 5.46 to 1.76 eV at an implanted dose of 1 × 1016 ions/cm2. It is shown that partial destruction of the original chemical bonding under ion implantation leads to the creation of new amorphous and graphite-like structures, which are confirmed by Raman spectroscopy. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:143,151, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20130 [source] Formation of carbon nanostructures and spatial-energy stabilization criterionJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008G. A. Korablev Abstract A spatial-energy criterion of structure stabilization is obtained. The computational results for 100 binary systems correspond to the experimental data. The basic regularity of organic cyclic compound formation is given and its application for carbon nanostructures is shown. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] High-dimensional solid-liquid phase diagrams involving compounds and polymorphsAICHE JOURNAL, Issue 10 2002Christianto Wibowo A systematic procedure for the generation and visualization of high-dimensional isobaric phase diagrams for systems exhibiting compound formation and/or polymorphism is presented. Such phase diagrams are useful in synthesizing crystallization-based separation processes for systems involving compounds and polymorphs, which are common in the production of pharmaceuticals. Polythermal as well as isothermal phase diagrams of multicomponent systems can be generated. Examples are provided to illustrate the procedure. [source] Effect of previous chilled storage on rancidity development in frozen horse mackerel (Trachurus trachurus)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2002Santiago P Aubourg Abstract Rancidity development during frozen storage (,20,°C) of an underutilised medium-fat-content fish species, horse mackerel (Trachurus trachurus), was studied. Special attention was given to the effect of previous chilled storage (0, 1, 3 and 5 days) on the quality of the frozen fish. For this, chemical (free fatty acid and conjugated diene contents; peroxide value, PV; thiobarbituric acid index, TBA-i; fluorescent compound formation) and sensory (rancid odour and taste) analyses were carried out. Hydrolytic rancidity showed an increase with frozen storage time; however, no effect of previous chilling time was observed on the frozen product. Oxidative rancidity measured by chemical (PV, TBA-i and fluorescence) and sensory (odour and taste) indices increased with frozen storage time and also with previous chilling time. Satisfactory quality was maintained up to 7 months of frozen storage of horse mackerel provided that a short chilling time (not longer than 3 days) was employed. © 2002 Society of Chemical Industry [source] Loss of tocopherols and formation of degradation compounds at frying temperatures in oils differing in degree of unsaturation and natural antioxidant contentJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2002Daniel Barrera-Arellano Abstract Samples of oils of different degrees of unsaturation, namely palm olein, olive oil, high-linoleic sunflower oil, high-oleic sunflower oil, rapeseed oil and soybean oil, were heated at 180,°C for 2, 4, 6, 8 and 10,h in the presence or absence of their natural antioxidants. Also, tocopherol-stripped oils were supplemented with ,-tocopherol (500,mg,kg,1), ,-tocopherol (500,mg,kg,1) or a mixture of ,-, ,-, ,- and ,-tocopherols (250,mg,kg,1 each) and heated under the same conditions. Losses of tocopherols and formation of polymeric triacylglycerols were followed. Total polar compounds were also evaluated after 10,h of heating. Results demonstrated that tocopherols were lost very rapidly, in the expected order, with ,-tocopherol being the least stable. Polymeric and polar compound formation during heating was inhibited to a variable extent, being more dependent on the natural content and type of tocopherols than on the degree of unsaturation of the oil. For example, polymeric and polar compound contents in soybean oil were significantly lower than those found in high-linoleic sunflower oil. However, the expected influence of the degree of unsaturation was evident when oils were unprotected or possessed identical initial antioxidant contents. Finally, levels of degradation compounds after 10,h of heating were not dependent on the remaining content of antioxidants. © 2002 Society of Chemical Industry [source] Thermoreversible Poly(vinylidene fluoride) Gels: A Precursor to Multiporous Polymeric MaterialsMACROMOLECULAR SYMPOSIA, Issue 1 2008D. Dasgupta Abstract Summary: The thermodynamics of gelation of poly(vinylidene fluoride)(PVF2) with camphor (CP) and ethylene carbonate (EC) suggest polymer-solvent compound formation. The presence of solvent molecules in the polymer crystalline phase of the gel is accordingly shown by wide angle X-ray diffraction studies. The dried gels exhibit porous network morphology. Thermoreversible gel of PVF2 in diethyl azelate is also exploited to create multiporous polymer foam. Porosity measurements with the dried PVF2 gels using Mercury intrusion porosimetry and nitrogen sorption ensure the presence of macro and mesopores in the same matrix although the mesoporosity in dried PVF2 -CP gels strongly depend on method of drying. [source] Encapsulation of magnetic self-assembled systems in thermoreversible gelsMACROMOLECULAR SYMPOSIA, Issue 1 2003Jean-Michel Guenet Abstract We describe two different ways of encapsulating within the fibrils of thermoreversible polymer gels the filaments of a supermolecular polymer formed by self-assembly of a bicopper complex. Heterogeneous nucleation is brought about with gels made from isotactic poly(styrene) while compound formation occurs with gels made from poly(hexyl isocyanate). These ways depend upon the interaction between the wings of the supermolecular polymer and the side groups of the polymer. In all cases, the filaments retain their 1-D structure. Preliminary results from magnetic susceptibility measurements show a striking difference between the pure and the encapsulated supermolecular polymer. [source] Study on the Interaction of Ketoconazole with Human and Bovine Serum Albumins by Fluorescence SpectroscopyCHINESE JOURNAL OF CHEMISTRY, Issue 12 2008Qing-Lian GUO Abstract The binding of ketoconazole to human serum albumin and bovine serum albumin was studied by using fluorescence and ultraviolet spectroscopy. The measurements were performed in 0.1 mol·L,1 phosphate buffer solution at pH=7.40±0.1. Decreasing of quenching constant was observed in association with temperature increase. Our findings show that the quenching mechanism of fluorescence of serum albumins by ketoconazole was static quenching because of compound formation. The thermodynamic parameters ,G, ,H, and ,S at different temperatures were calculated, showing that the electrostatic interactions and hydrophobic interaction are the main forces for the binding of ketoconazole to serum albumins. The distance r between the donor (Trp-214) and acceptor (ketoconazole) was obtained according to fluorescence resonance energy transfer theory. [source] Molecular modelling of inclusion compounds from hydrophobic dyes and ,-cyclodextrinCOLORATION TECHNOLOGY, Issue 4 2009Ahmed El-Shafei This paper arises from studies aimed at developing new approaches to combining the fabric formation and coloration steps of fabric processing. A key aspect of these studies involved the evaluation of cyclodextrin (CD)-based compounds as hosts for dye molecules that could be released onto a fabric surface following fabric formation. In this study, experimental data from wide-angle X-ray diffraction and differential scanning calorimetry experiments were used in tandem with molecular modelling studies to confirm the formation of ,-CD,dye complex inclusion compounds and to demonstrate the utility of parameterised model number 3 (PM3) semi-empirical molecular modelling methods for predicting the nature of the preferred ,-CD,dye inclusion compounds. Calculations revealed that the inclusion compounds containing two dye molecules was preferred over the inclusion compound containing one dye molecule. Further, molecular modelling of the inclusion compound obtained using ,-CD linked to an epichlorohydrin-based oligomer and commercial disperse dyes showed inclusion compound formation to be an energetically favourable process. [source] Organotins-promoted peroxidation of unsaturated fatty acids: A new antioxidative scavenger for promotersHETEROATOM CHEMISTRY, Issue 6 2006Elena R. Milaeva The organotin compounds RnSnX4- n are promoters of lipids peroxidation. The influence of (CH3)2SnCl2, (C2H5)2SnCl2, and SnCl2 upon the radical chain oxidation of oleic acid as model substrate R,H for lipid peroxidation in the simultaneous presence of porphyrins (free bases of meso -tetrakis(3,5-di- tert -butyl-4-hydroxyphenyl)porphyrin (R,4PH2) and of meso -tetraphenylporphyrin (TPPH2)) has been studied. The monitoring of the unsaturated acid peroxidation level has been performed by the determination of the total concentration of isomeric hydroperoxides as well as of the thiobarbituric acid reactive substances, as markers of carbonyl compounds formation following the hydroperoxides decomposition. The organotin compounds demonstrate prooxidative activity. The promoting effect of these compounds decreases in the presence of TPPH2. The free-base porphyrin R,4PH2, containing the antioxidative phenolic moieties (2,6-di- tert -butylphenol), demonstrates the acute inhibitory effect upon the acid's peroxidation. The analogous results have been achieved when compared with the influence of CH3HgI and HgCl2 upon the acids peroxidation of oleic acid in the presence of porphyrins. This fact points out that meso- tetrakis(3,5-di- tert -butyl-4-hydroxyphenyl)porphyrin shows the activities of both the antioxidant and of the scavenger for metals and might be used as a new antioxidative scavenger preventing lipids peroxidation. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:475,480, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20269 [source] | |||||||||||||