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881.
Maria?Jo?o?RochaEmail author Eduardo?Rocha Albina?D?Resende Alexandre?Lobo-da-Cunha 《BMC biochemistry》2003,4(1):2
Background
This study was aimed primarily at testing in the liver of brown trout (Salmo trutta ) spectrophotometric methods previously used to measure the activities of catalase and hydrogen peroxide producing oxidases in mammals. To evaluate the influence of temperature on the activities of those peroxisomal enzymes was the second objective. A third goal of this work was the study of enzyme distribution in crude cell fractions of brown trout liver. 相似文献882.
883.
Alvarez-Idaboy JR Galano A Bravo-Pérez G Ruiz ME 《Journal of the American Chemical Society》2001,123(34):8387-8395
The reactions of NO(3) with formaldehyde, acetaldehyde, propanal, n-butanal, and isobutanal have been modeled using accurate ab initio and hybrid DFT methods with large basis sets. The results clearly indicate that the reaction is a simple aldehydic H atom abstraction; no adduct was found to support the idea of a complex mechanism. Alternative hydrogen abstractions were modeled for the alpha carbon hydrogen atoms and for the Cbeta of n-butanal; the differences in activation energies ruled out the possibility that competitive abstraction could be responsible for the anomalous increase of the rate constants with the size of aldehydes. The anomalous behavior was found to be a consequence of the preexponential factor increase, due to the enlargement of the internal rotation partition functions with the size of the aldehydes. The reaction rate constants, calculated using the conventional transition-state theory as applied to a proposed simple mechanism, reproduce remarkably well the reported experimental results. Consideration of the internal rotation partition functions is shown to be essential for the determination of the preexponential parameters and thus for the correct calculation of the rate constants. The tunneling correction was found negligible due to the features of the transition vector. 相似文献
884.
Margarita R. Marín‐Yaseli Dr. Elena González‐Toril Cristina Mompeán Dr. Marta Ruiz‐Bermejo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12785-12799
The origin of life is one of the fundamental questions in science. Eschenmoser proposed the “glyoxylate scenario”, in which plausible abiotic synthesis pathways were suggested to be compatible with the constraints of prebiotic chemistry. In this proposal, the stem compound is HCN. In this work, we explore the “glyoxylate scenario” through several syntheses of HCN polymers, paying particular attention to the role of the aqueous aerosols, together with statistical methods, as a step to elucidate the synthetic problem of the origin of life. The soluble and insoluble HCN polymers synthetized were analyzed by GC‐MS. We identified, for the first time, glyoxylic acid in these polymers, together with some constituents of the reductive tricarboxylic acid cycle, amino acids and several N‐heterocycles. The findings presented herein, as the first global approach to the “glyoxylate scenario”, give full effect to this hypothesis and prove that aqueous aerosols could play an important role in this plausible scene of the origin of life. 相似文献
885.
The Similarity Renormalization Group reduces the off-shellness by driving the evolved interaction towards a diagonal band. We analyze the infrared limit and the corresponding on-shell interactions and its consequences for light nuclei. Using a harmonic oscillator shell model we obtain a Tjon line B α = 4B t ? 3B d which can be understood from a combinatorics counting of nucleon pairs and triplets in the triton and α-particle and compares favorably with realistic calculations. 相似文献
886.
Tainá Olivieri Chaves Akira Iwahara Luiz Tauhata Eduarda Alexandre Rezende Amanda Ribeiro Correia Estela Maria de Oliveira 《Journal of Radioanalytical and Nuclear Chemistry》2012,293(1):211-216
The radionuclide 131I has been increasingly used in nuclear medicine therapy procedures. Nowadays, the 131I source administered to the patient is manufactured in two different geometries: solution and capsules. The purpose of this study is the accurate measurement of the activity present in a 131I capsule without destroys it. The methodology to determine the capsules activity is to obtain the calibration factor of an IG12 secondary standard activity measurement system based on the IG12 well-type ionization chamber set up at Brazilian national metrology laboratory for ionizing radiation (LNMRI) of institute of radiation protection and dosimetry (IRD).The result obtained, 6.4670?±?0.0381?×?10?18?A?Bq?1, is quite similar to the calibration factor of the 131I solution contained in the standard ampoule geometry, 6.4515?±?0.0368?×?10?18?A?Bq?1. After obtaining the calibration factor it was used to measure 131I therapy capsules in order to check the performance of radionuclide calibrators of some Brazilian nuclear medicine centers. 相似文献
887.
Luminescent Thermometers: A New Generation of Primary Luminescent Thermometers Based on Silicon Nanoparticles and Operating in Different Media (Part. Part. Syst. Charact. 10/2016)
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888.
A preparation of bis-lactams is described from α-ketols and bis-cyanamides in the presence of sodium ethoxide at room temperature. One of these compounds leads to an unsaturated derivative by condensation with furfural, or to a saturated analogue via catalytic hydrogenation. 相似文献
889.
890.
Alexandre Dhotel Laurent Delbreilh Boulos Youssef Jinyue Jiang Gérard Coquerel Jean-Marc Saiter Li Tan 《Journal of Thermal Analysis and Calorimetry》2013,112(1):301-305
We report here a simple pathway to thermally assemble acene-based molecules into large crystals without modification of their chemical structures. Differential scanning calorimetry was used to characterize properly thermal events occurring during successive heating and cooling processes. More interestingly, observations by means of polarized light microscopy (POM) revealed that a spontaneous formation of screw dislocations within crystals during the isothermal treatment triggered a structural reorganization by forming large and well-defined spiral architectures. After this reorganization, new crystals showed an excellent ordering in both vertical and horizontal directions. Due to the richness in pi-electrons of acene-based molecules, we expect this work of importance to organic electronics, especially in the design of new molecular building blocks and investigation of their assembly into sophisticated supramolecular structures. 相似文献