Search results for "Nuclear Magnetic Resonance"
showing 10 items of 1743 documents
Histaminanaloge, 27. Mitt. Bis (2,2′-histamine)
1985
Es wurden p-Phenylen-bis(2,2′-histamin) (6a), Ethylen-bis(2,2′-histamin) (6b), Tetramethylen-bis(2,2′-histamin) (6c) und Hexamethylen-bis(2,2′-histamin) (6d) dargestellt und auf Histamin-H1-und H2-agonistische Aktivitat untersucht. Histamine Analogues, XXVII: Bis(2,2′-histamines) p-Phenylenebis(2,2′-histamine) (6a), ethylenebis(2,2′-histamine) (6b), tetramethylenebis(2,2′-histamine) (6c), and hexamethylenebis(2,2′-histamine) (6d) were prepared and tested for histamine H1,-and H2-agonistic activity.
The first sorbicillinoid alkaloids, the antileukemic sorbicillactones A and B, from a sponge-derived Penicillium chrysogenum strain
2005
The saltwater culture of a Penicillium chrysogenum strain isolated from the Mediterranean sponge Ircinia fasciculata yielded three new sorbicillin-derived compounds (1-3), whose structures were elucidated mainly by 2D NMR and mass spectrometry. Among them, sorbicillactones A (1) and B (2) are the first sorbicillinoid natural products that contain nitrogen. Compound 1 is anti-HIV active and it exhibits a strong cytotoxic activity against L5178y leukemic cells, combined with a relatively low toxicity to cervical carcinoma HeLa S3 cells and pheochromocytoma PC 12 cells. The absolute configurations of I and 2 were elucidated by quantum chemical calculation of circular dichroism (CD) spectra. An…
ALANINE/ESR DOSIMETRY FOR TOTAL BODY IRRADIATION USING AN ANTHROPOMORPHIC PHANTOM
2016
Introduction: Total Body Irradiation (TBI) is a technique widely used in the radiation blood-oncology in the treatment of patients that need bone marrow transplantation or peripheral stem cell transplantation. This technique has some limitations such as the lack of homogeneity of the dose distribution (which may show variations of 20% in the different areas), irradiation of critical organs such as the lungs, the liver, the intestine and the eye-lens which can receive a dose comparable to that nominal and require appropriate shielding and a proper evaluation of the dose absorbed by them. The positive outcome of this type of radiation therapy is strictly related to a precise and accurate meas…
Anomalous temperature dependence of the IR spectrum of polyalanine
1997
Abstract We have studied the temperature dependence of the infrared spectra of acetanilide (ACN), tryptophan–(alanine) 15 , and tyrosine–(alanine) 15 . No sidebands of the amide-I vibration were observed in the polypeptides, but two anomalous sidebands of the NH stretch with a similar temperature dependence as that of the anomalous amide-I vibrational mode at 1650 cm −1 of crystalline ACN were detected. Fermi resonance combined with the appearance of a red-shifted sideband of NH stretch through coupling to lattice modes seems to explain this band structure. Observations are indicative of excitons that may occur in polypeptides as well as in single crystals of ACN.
Pitfalls to be considered on the metabolomic analysis of biological samples by HR-MAS
2014
HR-MAS (High-Resolution Magic AngleSpinning) is considered a powerfultechnique for metabolomic studies ofbiological samples that provides “intact”tissue spectra (Cheng et al., 1998; Waterset al., 2000; Sitter et al., 2002; Martinez-Bisbal et al., 2004; Payne et al., 2006;Coen et al., 2007; Bathen et al., 2010).The performance of HR-MAS, fol-lowed by quantitative histopathology hasdemonstrated that, despite some changes,HR-MAS can preserve approximately thetissue histopathologic features producingwell-resolved spectra of cellular metabo-lites (Cheng et al., 2000). Nevertheless,therearesomeaspectsarousedintheliter-ature about the possible biochemical andstructural changes that can occur durin…
Synthesis, characterization of diorganotin(IV) complexes of N-(2-hydroxyarylidene)aminoacetic acid and antitumour screening in vivo in ehrlich ascite…
2001
Some new diorganotin(IV) complexes have been prepared by reacting potassium N-(2-hydroxyarylidene)aminoacetate with R2SnCl2(R = Me,nBu,Ph). The complexes have been characterized by 1H,13C,119Sn NMR, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analysis. In the solid state, the complexes possess penta- and hexa-coordinated tin centres. The hexa-coordinated tin complexes were found to dissociate in solution, giving rise to penta-coordinated species as revealed by 119Sn NMR spectroscopy. Antitumour screening in vivo of the complexes L4snPh2,L4SnPh2· Ph3SnCl and L4SntBU2·t Bu2SnCl2 (L4 = N-(2-hydroxyacetophenone)aminoacetate) is also reported. Copyright © 2001 …
Oxidation-driven changes of the in-plane magnetic surface anisotropies of the Fe(110)/Al interface
2003
Abstract Thin epitaxial iron films grown on W(1 1 0) were covered by ultrathin epitaxial aluminium layers of varying thicknesses from 0.2 to 0.6 nm and subsequently naturally oxidized in situ with oxygen exposures up to 150 L. Correlations between the oxidation states of the Al covers and changes of the in-plane magnetic anisotropies at the Fe(1 1 0)/Al interface were discussed on the basis of results from X-ray photoelectron spectroscopy and longitudinal magneto-optical Kerr magnetometry measurements. The Al coverage decreases the second-order in-plane surface anisotropy of the Fe(1 1 0) surface. Whereas for the thinnest Al covers, the second-order in-plane magnetic surface anisotropy decr…
Optically detected magnetic resonance studied via the blue luminescence of Ti-doped
1998
The UV-excited blue and green luminescence bands of Ti:sapphire are characterized by ODMR. These emission bands are attributed to two centres, which show very similar properties and are created as a result of a charge-transfer transition of an electron from to ions. In both centres, the d electron of and the hole of are strongly coupled and form triplet states. Doublet systems can be ruled out as sources of the blue-green luminescence. The angular dependence of the ODMR can be explained with an appropriate spin Hamiltonian assuming orthorhombic local symmetry. The orientation of the principal axes of the g-tensor and the crystal-field tensor, found for both centres, suggest that the hole is…
Gradient-echo and CRAZED imaging for minute detection of Alzheimer plaques in an APPV717I x ADAM10-dn mouse model.
2007
Different strategies to visualize amyloid plaques with MRI at 17.6 Tesla were investigated in a novel mouse model of Alzheimer's disease (AD). Large iron-containing plaques were observed in the thalamus, but cortical plaques did not show iron deposits. Plaques in the thalamus were visualized in vivo with the use of low-resolution, 3D gradient-echo (GRE) imaging in 82 s, and with 94-microm resolution in 34 min. The feasibility of obtaining bright contrast from plaques using the COSY revamped with asymmetric z-GRE detection (CRAZED) technique was investigated in experiments on fixed brains. The original CRAZED approach provided reduced signal near the plaques (similarly to GRE imaging) and ad…
H2-Antihistaminika, 36. Mitt. Isolamtidin und Analoge
1987
Isolamtidin (9a), ein Stellungsisomer des Lamtidins (8a), sowie die analogen N3-substituierten 1-Methyl-1H-1,2,4-triazol-3,5-diamine 9e-i, k wurden durch spezifische Synthese dargestellt und am isolierten Meerschweinchenvorhof und an der histaminstimulierten Sauresekretion der narkotisierten Ratte auf H2-antagonistische Wirkung untersucht. H2-Antihistaminics, XXXVI: Isolamitidine and Analogues Isolamitidine (9a), a position isomer of lamtidine (8a), as well as the analogous N3-substituted 1-methyl-1H-1,2,4-triazole-3,5-diamines 9e-i, k were prepared and tested for H2-antagonistic activity on the isolated guinea-pig atrium and towards the histamine-stimulated acid secretion of the anaestheti…