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61.
Klaus A Tiddy GJ Touraud D Schramm A Stühler G Kunz W 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):16871-16883
The formation of microemulsions with triglycerides at ambient conditions can be improved by increasing the surfactant-water and surfactant-oil interactions. Therefore, extended surfactants were developed, which contain hydrophilic/lipophilic linkers. They have the ability to stretch further into the oil and water phase and enhance the solubility of oil in water. In this work, the phase behavior of a chosen extended surfactant (C(12-14)-PO(16)-EO(2)-SO(4)Na, X-AES) in H(2)O/D(2)O at high surfactant concentrations (30-100 wt %) and at temperatures between 0 and 90 °C is studied for the first time. The lyotropic liquid crystals formed were determined by optical microscopy, small-angle X-ray scattering (SAXS), and (2)H and (23)Na NMR, and a detailed phase diagram of the concentrated area is given. The obtained mesophases are a hexagonal phase (H(1)), at low temperatures and small concentrations, a lamellar phase (L(α)) at high temperatures or concentrations, a bicontinuous cubic phase (V(2)) as well as a reverse hexagonal phase (H(2)). To our knowledge, this is the first surfactant that forms both H(1) and H(2) phases without the addition of a third compound. From the (2)H NMR quadrupole splittings of D(2)O, we have examined water binding in the L(α) and the H(2) phases. There is no marked difference in the bound water between the two phases. Where sufficient water is present, the number of bound water molecules per X-AES is estimated to be ca. 18 with only small changes at different temperatures. Similar results were obtained from the (23)Na NMR data, which again showed little difference in the ion binding between the L(α) and the H(2) phases. The X-ray diffraction data show that X-AES has a much smaller average length in the L(α) phase compared to the all-trans length than in the case for conventional surfactants. At very high surfactant concentrations an inverse isotropic solution (L(2)), containing a small fraction of solid particles, is formed. This isotropic solution is clearly identified and the size of the reversed micelles was determined using (1)H NMR measurements. Furthermore, the solid particles within the L(2) phase and the neat surfactant were analyzed. The observed results were compared to common conventional surfactants (e.g., sodium dodecyl sulfate, sodium lauryl ether sulfate, and sodium dodecyl-p-benzene sulfonate), and the influence of the hydrophilic/lipophilic linkers on the phase behavior was discussed. 相似文献
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Anette Henriksen Uffe Anthoni Tommy H. Nielsen Jan Srensen Carsten Christophersen Michael Gajhede 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):113-115
The crystal structure of the non‐ribosomal lipoundecapeptide tensin from Pseudomonas fluorescens has been solved as an ethyl acetate/bis‐water solvate (tensin ethyl acetate dihydrate, C67H115N12O20·C4H8O2·2H2O) to a resolution of 0.8 Å. The primary structure of tensin is β‐hydroxydecanoyl‐d ‐Leu‐d ‐Asp‐d ‐allo‐Thr‐d ‐Leu‐d ‐Leu‐d ‐Ser‐l ‐Leu‐d ‐Gln‐l ‐Leu‐l ‐Ile‐l ‐Glu. The peptide is a lactone linking the Thr3 Oγ atom to the C‐terminal C atom. The stereochemistry of the β‐hydroxy acid has been shown to be S. The peptide shows structural resemblance to the non‐ribosomal cyclic lipopeptide fengycin from Bacillus subtilis. The structure of tensin is essentially helical (310‐helix), with the cyclic peptide wrapping around a hydrogen‐bonded water molecule. The lipopeptide is amphipathic in good agreement with its function as a biosurfactant. 相似文献
64.
Dr. Ulrike Krug Anika Gloge Dr. Peter Schmidt Dr. Johanna Becker-Baldus Dr. Frank Bernhard Dr. Anette Kaiser Cindy Montag Marcel Gauglitz Dr. Sergey A. Vishnivetskiy Prof. Dr. Vsevolod V. Gurevich Prof. Dr. Annette G. Beck-Sickinger Prof. Dr. Clemens Glaubitz Prof. Dr. Daniel Huster 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):24062-24070
65.
An efficient protocol for the epoxidation of acid-and acid/base-sensitive alkenes with m-chloroperoxybenzoic acid and using 2,6-di-tert-butylpyridine as a buffer is described. 相似文献
66.
Anette Giesemann 《Isotopes in environmental and health studies》2013,49(2):89-90
Es wird über die Entwicklung energie- und richtungsunabhängiger Ionisationskammern sowie über die Konzeption und Wirkungsweise des Dosimeters VA-J-18 berichtet, das als Dosis- und Dosisleistungsmeβgerät vorwiegend für den klinischen Einsatz in der Strahlentherapie vorgesehen ist. Auf Grund des hohen MeβSumfangs ist es atich für die meβtechnische Überwachung strahlenmedizinischer oder -biologischer Experimente sowie für Strahlenschutzmessungen und Aktivitätsbestimmungen geeignet. 相似文献
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Nondestructive detection of internal bruise and spraing disease symptoms in potatoes using magnetic resonance imaging 总被引:2,自引:0,他引:2
Thybo AK Jespersen SN Laerke PE Stødkilde-Jørgensen HJ 《Magnetic resonance imaging》2004,22(9):1311-1317
Magnetic resonance imaging (MRI) was applied to detect nonvisible internal bruise and spraing symptoms and to get insight on the chemical and anatomical causes of such defects. Cultivar Saturna with internal bruise and cultivar Estima with spraing symptoms were investigated by comparison of different MR images as proton density-, T(1)- and T(2)-weighted images and T(2) maps. In all these types of MR images, it was possible to identify internal bruise and spraing spots in the potatoes, where these phenomena were present. When combining the information in the MR images, the interior of the internal bruise was characterised as being very dry (low signal in the proton-weighted image) with a small amount of highly mobile water in the shell around the bruise (high signal in T(2)-weighted image and high relaxation time in T(2) map). The spraing spots were more diffuse; however, the dry interior and highly mobile water around the spraing dots were somewhat similar to the appearance of internal bruise but resembled more the appearance of human tumour tissue than bruise disorders in, for example, fruits. In conclusion, this study demonstrated that MRI can detect nonvisible internal bruise and spraing symptoms in potatoes, which has not been published before. MRI may, therefore, be an appropriate method for detecting and for studying developmental changes of such disorders and related disorders during postharvest storage in future experiments. 相似文献
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