Search results for "methane"
showing 10 items of 1763 documents
Determination of lecithin and soybean oil in dietary supplements using partial least squares-Fourier transform infrared spectroscopy.
2008
Lecithin and soybean oil in dietary supplements were determined by Fourier transform infrared spectrometry transmission measurements in dichloromethane in combination with a partial least squares (PLS) regression. Two different PLS models were developed, using 16 synthetic mixtures of analytes in dichloromethane, making measurements in the spectral range from 931.8 to 1252.3 cm(-1) for lecithin and from 911.4 to 1246.9 cm(-1) and 1695.3 to 1774.5 cm(-1) for soybean oil. Seven products from the Spanish market with lecithin concentrations between 21.1% and 99.1% and soybean oil concentrations between 0% and 37.2% were analyzed by the proposed method and the data was compared to a chromatograp…
Secondary structure conformation of hydroperoxide lyase from green bell pepper, cloned in Yarrowia lipolytica, and its activity in selected media
2008
International audience; Circular dichroism (CD) spectroscopy of secondary structure conformation of the purified green bell pepper hydroperoxide lyase (HPL), cloned in the yeast Yarrowia lipolytica, was investigated. The CD spectra of HPL in iso-octane, obtained at 60 °C, in the presence of the reducing agent dithiothreitol showed dramatic increase in α-helix content. The enzyme conformation remained unchanged over a range of pH values of 5.0–7.0. Using 13-hydroperoxide of linoleic acid (13-HPOD) as substrate, the biocatalysis of HPL in organic solvent media, including chloroform, dichloromethane, hexane, iso-octane, octane and toluene, was investigated. The results indicated an increase in…
Comparative biological evaluation and G-quadruplex interaction studies of two new families of organometallic gold(I) complexes featuring N-heterocycl…
2020
Experimental organometallic gold(I) compounds hold promise for anticancer therapy. This study reports the synthesis of two novel families of gold(I) complexes, including N1-substituted bis-N-heterocyclic carbene (NHC) complexes of general formula [Au(N1-TBM) 2]BF 4 (N1-TBM = N1-substituted 9-methyltheobromin-8-ylidene) and mixed gold(I) NHC-alkynyl complexes, [Au(N1-TBM)alkynyl]. The compounds were fully characterised for their structure and stability in aqueous environment and in the presence of N-acetyl cysteine by nuclear magnetic resonance (NMR) spectroscopy. The structures of bis(1-ethyl-3,7,9-trimethylxanthin-8-ylidene)gold(I), (4-ethynylpyridine)(1,9-dimethyltheobromine-8-ylidene)gol…
Metal NHC Complexes with Naphthalimide Ligands as DNA-Interacting Antiproliferative Agents
2017
Naphthalimide-based N-heterocyclic carbene (NHC) complexes of the type [(1,5-cyclooctadiene)(NHC)RhCl)] (4 a-c), [(p-cymene)(NHC)RuCl2 )] (5 a-c), and [(NHC)CuBr] (6 a-c) were synthesized and investigated as antiproliferative agents that target DNA. The cytotoxic effects were largely driven by the naphthalimide structure, which is a DNA-intercalating moiety. Regarding the metal center, the highest activities were observed with the rhodium complexes, and cytotoxic activity was significantly lower for the ruthenium derivatives. The stable coordination of the NHC ligands of selected complexes 4 b and 5 b in solution was confirmed, and their DNA binding properties were studied by UV/Vis spectro…
Liquid chromatography/atmospheric pressure chemical ionization-mass spectrometric analysis of benzoylurea insecticides in citrus fruits.
2000
A liquid chromatography (LC) method for the quantitative determination of three benzoylurea insecticide residues (diflubenzuron, flufenoxuron and hexaflumuron) in citrus fruits is described. Residues were successfully separated on a C18 column by methanol/water gradient elution. Detection was by negative-ion, selected-ion monitoring atmospheric pressure chemical ionization-mass spectrometry (APCI-MS); the main ions were [M - H]-, and the secondary fragment ions were [M - H - HF]-. Useful confirmatory information can thus be obtained at low extraction voltages from losses of HF. Detection limits for standard solutions were 10 fg injected and good linearity and reproducibility were obtained. …
An inducible mouse model of colon carcinogenesis for the analysis of sporadic and inflammation-driven tumor progression.
2007
Colorectal cancer is a life-threatening disease that can develop spontaneously or as a complication of inflammatory bowel diseases. Mouse models are essential tools for the preclinical testing of novel therapeutic options in vivo. Here, we provide a highly reliable protocol for an experimental mouse model to study the development of colon cancers. It is based on the mutagenic agent azoxymethane (AOM), which exerts colonotropic carcinogenicity. Repeated intraperitoneal administration of AOM results in the development of spontaneous tumors within 30 weeks. As an alternative option, inflammation-dependent tumor growth can be investigated by combining the administration of AOM with the inflamma…
A variant of Smurf2 protects mice against colitis-associated colon cancer by inducing transforming growth factor β signaling.
2011
Background & Aims Transforming growth factor (TGF)-β signaling, which is down-regulated by the E3 ubiquitin ligase Smad ubiquitin regulating factor 2 (Smurf2), promotes development of cancer. We identified a splice variant of Smurf2 (ΔE2Smurf2) and investigated its role in colon carcinogenesis in mice. Methods Colitis-associated colon cancer was induced in mice by administration of azoxymethane, followed by 3 cycles of oral administration of dextran sodium sulfate. Messenger RNA levels of Smurf2 in colon tumors and control tissue were measured by quantitative polymerase chain reaction; lymphocyte and cytokine levels were measured in tumor and tissue samples. Results Tumor-infiltrating CD4 +…
UKIRT Observations of the Impact and Consequences of Comet Shoemaker–Levy 9 on Jupiter☆
1997
The observation of Comet Shoemaker-Levy 9's collision with Jupiter in July of 1994 by the United Kingdom Infrared Telescope (UKIRT) produced spectroscopic data of high quality. Analysis of the data for Impact C has produced the first temperature curve that covers such an event, from the first visibility of the plume above the limb through to the settling down of the ejected gas onto the upper jovian atmosphere. Temperatures derived from methane emission show that 5 min after impact, a plume some 6500 km across was heated to similar to 1400 K. At its maximum spatial extent similar to 12 min after impact, a region of Jupiter's atmosphere similar to 45,000 km west from the impact site of the m…
The partition sum of methane at high temperature
2008
11 pages, 4 Tables, 3 Figures Computer code on line at http://icb.u-bourgogne.fr/JSP/TIPS.jsp; International audience; The total internal partition function of methane is revisited to provide reliable values at high temperature. A multi-resolution approach is used to perform a direct summation over all the rovibrational energy levels up to the dissociation limit. A computer code is executable on line at the URL : http://icb.u-bourgogne.fr/JSP/TIPS.jsp to allow the calculation of the partition sum of methane at temperatures up to 3000 K. It also provides detailed information on the density of states in the relevant spectral ranges. The recommended values include uncertainty estimates. It is …
Aliphatic Hyperbranched Copolyesters by Combination of ROP and AB2-Polycondensation
2005
Hyperbranched aliphatic copolyesters have been prepared by the copolymerization of e-caprolactone and 2,2-bis(hydroxymethyl)butyric acid (AB 2 -monomer), catalyzed by (i) HfCl 4 (THF) 2 and (ii) diphenylammonium trifluoromethanesulfonate (DPAT), respectively. In both cases, copolymerization by combined ROP/AB 2 -Polycondensation was achieved. The degree of branching (DB) and consequently the density of functional groups of the resulting copolyesters were controlled by the comonomer ratio in the feed. Molecular weights in the range M n =22 000-166 000 g mot -1 (GPC, PS standards) were obtained, with apparent polydispersity indices of 1.20 to 1.95. The DB was in the range 0.03-0.35. Remarkabl…