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1.
F. Trandafir P. Heerdt M. Fittipaldi E. Vinck S. Dewilde L. Moens S. Van Doorslaer 《Applied magnetic resonance》2007,31(3-4):553-572
In this work, the high-spin ferric form of the E7Q mutant of human neuroglobin (E7Q-NGB) is studied by X-band continuous-wave electron paramagnetic resonance (CW EPR) and hyperfine sublevel correlation (HYSCORE) spectroscopy. It is shown that the use of matched pulses in the HYSCORE experiment is essential to observe the nitrogen spectral contributions. The validity of approximating the high-spin Fe(III) system (S=5/2) as an effectiveS=1/2 system is tested and the consequences for the HYSCORE simulations are highlighted. Comparative HYSCORE experiments combined with deuterium exchange experiments for aquometmyoglobin and ferric E7Q-NGB clearly show that the heme iron of the latter protein is pentacoordinated, lacking the distal water. Furthermore, CW EPR experiments show that, at high pH, the E10K residue is coordinating to the heme iron in this globin. These observations are corroborated by resonance Raman experiments and could also be reproduced for other E7 mutants of human and mouse neuroglobin. Finally, the proton and nitrogen hyperfine and nuclear quadrupole parameters obtained for ferric E7Q-NGB are discussed in detail. 相似文献
2.
Budrugeac P. Trandafir Viorica Albu Madalina Georgiana 《Journal of Thermal Analysis and Calorimetry》2003,72(2):581-585
The methods of the thermal analysis (TG, DTG and DTA) were used in order to investigate the effect of the hydration degree
on the thermal behaviour of some collageneous matrices. It was pointed out that the degradation of hydrated collagen in the
temperature range 20-400°C occurs through two successive processes accompanied by mass losses. The first process, consisting
in the collagen dehydration, is endothermic and takes place in the temperature range ≈25 - ≈125°C. The second process is exothermic
and consists in the decomposition and/or thermo-oxidation of dry collagen. The thermal parameters of both processes depend
on the hydration degree of collagen. The observed dependencies show that the hydrothermal and thermo-oxidative stability of
collagen are strongly correlated with its water content.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Belz J Cousins RD Diwan MV Eckhause M Ecklund KM Hancock AD Highland VL Hoff C Hoffmann GW Irwin GM Kane JR Kettell SH Klein JR Kuang Y Lang K Martin R May M McDonough J Molzon WR Riley PJ Ritchie JL Schwartz AJ Trandafir A Ware B Welsh RE White SN Witkowski MT Wojcicki SG Worm S 《Physical review letters》1996,76(18):3277-3280
4.
Tiberiu-M. Gianga Edwige Audibert Anamaria Trandafir Gabriele Kociok-Khn G. Dan Panto 《Chemical science》2020,11(35):9685
We report herein the first all-donor aromatic [2]catenane formed through dynamic combinatorial chemistry, using single component libraries. The building block is a benzo[1,2-b:4,5-b′]dithiophene derivative, a π-donor molecule, with cysteine appendages that allow for disulfide exchange. The hydrophobic effect plays an essential role in the formation of the all-donor [2]catenane. The design of the building block allows the formation of a quasi-fused pentacyclic core, which enhances the stacking interactions between the cores. The [2]catenane has chiro-optical and fluorescent properties, being also the first known DCC-disulphide-based interlocked molecule to be fluorescent.An all-donor [2]catenane has been synthesised via dynamic combinatorial chemistry. It features stacked benzodithiophenes which are quasi-pentacyclic through hydrogen bonding. 相似文献
5.
Mihai Todica Traian Stefan Diana Trandafir Simion Simon 《Central European Journal of Physics》2013,11(7):928-935
The effects of gamma radiation on the local structure of PVA membranes containing TiO2 were investigated by ESR and XRD methods. An intense ESR signal is observed after irradiation at 16 KGy dose. This signal appears only for irradiated samples and it is associated with the breaking of the polymeric chain, followed by local reorganization of the polymeric segments and the apparition of the unpaired electrons and free radicals. The intensity of the signal decreases with the concentration of TiO2, indicating a shielding effect of the dopand. That the modification of local order of the polymeric chains has been modified after irradiation is confirmed by XRD method. 相似文献
6.
Local order changes determined by Fe2O3 (0–20 mol%) addition to Bi2O3–Ga2O3 matrix in glass and vitroceramic samples were investigated by X-ray diffraction (XRD), electron paramagnetic resonance (EPR) and Fourier transform infrared (FTIR) spectroscopies. Glass samples were prepared using the melt-quench technique. The vitroceramic samples were obtained by crystallization, as a result of the heat treatment applied on glass samples. The glass network mainly consists of [BiO6] octahedral units. After heat treatment induced crystallization, [BiO3] pyramidal units are predominant in samples. As evidenced by electron spin resonance, the Fe3+ ions surrounding is characterized by low crystal fields, excepting the vitreous sample with the lowest Fe2O3 content, wherein the Fe3+ ions occupy sites of low symmetry, characterized by high crystal fields. 相似文献
7.
The aim of this paper is to solve p-median problems with an additional coverage constraint. These problems arise in location applications, when the trade-off between distance and coverage is being calculated. Three kinds of heuristic algorithms are developed. First, local search procedures are designed both for constructing and improving feasible solutions. Second, a multistart GRASP heuristic is developed, based on the previous local search methods. Third, by employing Lagrangean relaxation methods, a very efficient Lagrangean heuristic algorithm is designed, which extends the well known algorithm of Handler and Zang, for constrained shortest path problems, to constrained p-median problems. Finally, a comparison of the computational efficiency of the developed methods is made between a variety of problems of different sizes. 相似文献
8.
Laura Trandafir Mioara Alexandru Mihai Constantin Anca Ioniţă Florina Zorilă Valentin Moise 《Radiation Physics and Chemistry》2012,81(9):1513-1515
EN ISO 11137 established regulations for setting or substantiating the dose for achieving the desired sterility assurance level.The validation studies can be designed in particular for different types of products. Each product needs distinct protocols for bioburden determination and sterility testing.The Microbiological Laboratory from Irradiation Processing Center (IRASM) deals with different types of products, mainly for the VDmax25 method. When it comes to microbiological evaluation the most challenging was cotton gauze. A special situation for establishing the sterilization validation method appears in cases of cotton packed in large quantities. The VDmax25 method cannot be applied for items with average bioburden more than 1000 CFU/pack, irrespective of the weight of the package. This is a method limitation and implies increased costs for the manufacturer when choosing other methods.For microbiological tests, culture condition should be selected in both cases of the bioburden and sterility testing. Details about choosing criteria are given. 相似文献
9.
Ioan Valentin Moise Marian Virgolici Constantin Daniel Negut Mihaela Manea Mioara Alexandru Laura Trandafir Florina Lucica Zorila Catalina Mihaela Talasman Daniela Manea Steluta Nisipeanu Maria Haiducu Zamfir Balan 《Radiation Physics and Chemistry》2012,81(8):1045-1050
Museums, libraries and archives are preserving documents that are slowly degrading due to the inherent ageing of the cellulose substrate or to the technological errors of the past (acid paper, iron gall ink). Beside this, large quantities of paper are rapidly damaged by biological attacks following natural disasters and improper storage conditions.The treatment of paper documents with ionizing radiation can be used for mass decontamination of cultural heritage items but conservators and restaurators are still reserved because of the radiation induced degradation.We conducted a study for establishing the dose needed for the effective treatment of paper documents, taking into account the biological burden and the irradiation effects on paper structure. We used physical testing specific to paper industry and less destructive analytical methods (thermal analysis).Our results show that an effective treatment can be performed with doses lower than 10 kGy. Old paper appears to be less affected by gamma radiation than recent paper but the sampling is highly affected by the non-uniform degree of the initial degradation status. The extent of testing for degradation and the magnitude of acceptable degradation should take into account the biological threat and the expected life time of the paper documents. 相似文献
10.
Noncrystalline and nanocomposite materials of (1?x)SiO2·xGeO2 system, with Si:Ge ratio from 8:1 to 2:1 (x?=?0.111; 0.142; 0.2; 0.333), initially obtained by sol?Cgel method, were characterized by thermal analyses, X-ray diffraction, nuclear magnetic resonance and Raman spectroscopy. According to DTA and XRD results, the noncrystalline state of the as-prepared samples is stable up to 1,000?°C and only after 30?min heat treatment at 1,200?°C the samples become partial crystalline, due to development of cristobalite and quartz nanocrystals. Solid-state 29Si MAS-NMR was employed in order to characterize the local structure around silicon as a function of composition and thermal history of the samples. The NMR data indicate the presence of Q2, Q3 and Q4 units in all samples. The fraction of the highly interconnected SiO4 tetrahedra increases both with germanium content and with annealing temperature. The Raman spectroscopy results evidence structural changes related to silicon- and germanium-oxygen units but also to their interconnection, that depend on Si:Ge ratio and annealing temperature. 相似文献