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41.
42.
Manganese lipoxygenase (Mn-LO) oxygenates linoleic acid (LA) to a mixture of the hydroperoxides—11(S)-hydroperoxy-9Z,12Z-octadecadienoic acid [11(S)-HPODE] and 13(R)-hydroperoxy-9Z,11E-octadecadienoic acid [13(R)-HPODE]- and also catalyzes the conversion of 11(S)-HPODE to 13(R)-HPODE via oxygen-centered (LOO•) and carbon-centered (L•) radicals [Hamberg, M., Su, C., and Oliw, E. (1998) Manganese Lipoxygenase.
Discovery of a Bis-allylic Hydroperoxide as Product and Intermediate in a Lipoxygenase Reaction, J. Biol. Chem. 273, 13080–13088]. The aims of the present work were to investigate whether 11-HPODE can also be produced by iron-dependent lipoxygenases
and to determine the enzymatic transformations of stereoisomers of 11-HPODE by lipoxygenases. Rice leaf pathogen-inducible
lipoxygenase, but not soybean lipoxygenase-1 (sLO-1), generated a low level of 11-HPODE (0.4%) besides its main hydroperoxide,
13(S)-HPODE, on incubation with LA. Steric analysis revealed that 11-HPODE was enriched with respect to the R enantiomer [74% 11(R)]. In agreement with previous results, 11(S)-HPODE incubated with Mn-LO provided 13(R)-HPODE, and the same conversion also took place with the methyl ester of 11(S)-HPODE. 11(R,S)-HPODE was metabolized biphasically in the presence of Mn-LO, i.e., by a rapid phase during which the 11(S)-enantiomer was converted into 13(R)-HPODE and a slow phase during which the 11(R)-enantiomer was converted into 9(R)-HPODE. sLO-1 catalyzed a slow conversion of 11(S)-HPODE into a mixture of 13(R)-HPODE (75%), 9(S)-HPODE (10%), and 13(S)-HPODE (10%), whereas 11(R,S)-HPODE produced a mixture of nearly racemic 13-HPODE (≈70%) and 9-HPODE (≈30%). The results showed that 11-HPODE can also
be produced by an iron-dependent LO and suggested that the previously established mechanism of isomerization of 11(S)-HPODE involving suprafacial migration of O2 is valid also for the isomerizations of 11(R)-HPODE by Mn-LO and of 11(S)-HPODE by sLO-1. 相似文献
43.
Mioara Băncescu 《控制论与系统》2016,47(7):602-615
For monitoring the status of project activities, project costs, and for controlling the project, the Earned Value Management system (EVM) is extensively used by both researchers and practitioners. However, using only EVM methodology to control a project schedule, the project manager will not know accurately when to take the appropriate corrective measures or when to exploit opportunities for the project. We suggest in this work using both EVM methodology and statistical process control (SPC) in order to better control a project schedule progress. Using the software R, a control chart for monitoring the Schedule Performance Index (SPI) individual observations is designed for the application of the study. We present results and conclusions about unusually slow or unusually fast work progress for a construction project, about the link between the schedule progress and the project team stages of development, and about the entry data necessary to design a project control chart for controlling the schedule of a project. 相似文献
44.
45.
C.?V.?Cristea C.?MoinetEmail author M.?Jitaru I.?C.?Popescu 《Journal of Applied Electrochemistry》2005,35(9):851-855
Nitroso compounds were electrogenerated from (1S, 2S)-2-amino-1-(4-nitrophenyl)-propane-1,3-diol derivatives (derivatives of p-nitrophenylserinol) in a “redox” flow cell equipped with two consecutive porous electrodes of opposite polarities. In spite. of the relative instability in methanol-acetate buffer of the hydroxylamine intermediates produced at the first porous electrode (cathode), the nitroso derivatives were prepared in good yields at the second one (anode). A coupling reaction between some nitroso derivatives and p-toluenesulphinic acid led to N-sulphonylphenylhydroxylamines. 相似文献
46.
E. Manea E. Budianu M. Purica D. Cristea I. Cernica R. Muller V. Moagar Poladian 《Solar Energy Materials & Solar Cells》2005,87(1-4):423
This paper presents the results of an experimental study regarding the increase in the efficiency of the silicon solar cells by texturing the front surface. Designing, patterning and surface etching processes led to refined structures with very low losses of the incident optical radiation. Photolithography has been used to generate patterns (disc hole) through the silicon dioxide layer grown at the beginning on silicon wafers. The holes (4 μm in diameter) have been uniformly distributed on the entire surface (2×2) cm2 and the distance between the hole centres was determined to be 20 μm. Semispherical walls have been defined in holes by isotropic etching up to join together of the wells. 相似文献
47.
Segmented biopolyurethanes for medical applications 总被引:1,自引:0,他引:1
Doina Macocinschi Daniela Filip Stelian Vlad Mariana Cristea Maria Butnaru 《Journal of materials science. Materials in medicine》2009,20(8):1659-1668
Polyurethanes are one of the most popular groups of biomaterials applied for medical devices. Their segmented block copolymeric
character endows them a wide range of versatility in terms of tailoring their physical properties, blood and tissue compatibility.
Polyester- and polyether-urethanes have been modified with hydroxypropyl cellulose aiming the change of their surface and
bulk characteristics to confer them biomaterial qualities. In this respect, dynamic contact angle measurements, dynamic mechanical
analyses accompanied by mechanical testing have been done. Platelet adhesion test has been carried out in vitro and the use
of hydroxypropyl cellulose in the polyurethane matrix reduces the platelet adhesion and therefore recommends them as candidates
for biocompatible materials. 相似文献
48.
Constantin Gaina Viorica Gaina Mariana Cristea 《Journal of Inorganic and Organometallic Polymers and Materials》2009,19(2):157-165
New poly(urethane–urea) varnishes containing tributyltin groups were prepared by the reaction of dibenzyldiisocyanate in excess
with a macrodiol (PEGA-2000), trimethylolpropane, diethylene glycol and a bisalcohol maleimide monomer containing tributyltin
carboxylate group. Tributyltin maleimide monomers were obtained from 4-{3,4-bis[(2-hydroxyethyl)sulfanyl]-2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl}benzoic acid and bis(tributyltin) oxide. Structure of monomers and polymers was confirmed by the IR, NMR spectroscopy
and elemental analysis. The polymer films were characterized by dynamic mechanical analysis (DMA), differential scanning calorimetry
(DSC), X-ray diffractions, thermogravimetric (TGA) and stress–strain measurements. 相似文献
49.
Teodora Gratiela Tihan Mioara Daniela Ionita Roxana Gabriela Popescu Dana Iordachescu 《Materials Chemistry and Physics》2009,118(2-3):265-269
The purpose of this study is to put in evidence the correlation between hydrophilic/hydrophobic balance and biocompatibility of PMMA–HA composites, in order to select the best composites for futures clinical applications. For this purpose, PMMA–HA cements with different compositions were prepared and static contact angle measurements, water absorption and gingival fibroblasts cell culture were performed and discussed. 相似文献
50.
Corneliu Hamciuc Elena Hamciuc Alina Mirela Ipate Mariana Cristea Lidia Okrasa 《应用聚合物科学杂志》2009,113(1):383-391
A series of aromatic copolyethers containing 1,3,4‐oxadiazole rings and fluorene groups was prepared by nucleophilic substitution polymerization technique of 9,9‐bis(4‐hydroxyphenyl)fluorene, 1 , or of different amounts of 1 and an aromatic bisphenol, such as 4,4′‐isopropylidenediphenol or phenolphthalein, with 2,5‐bis(p‐fluorophenyl)‐1,3,4‐oxadiazole. The polymers were easily soluble in polar solvents like N‐methylpyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and chloroform and can be cast from solutions into thin flexible films. They showed high thermal stability, with decomposition temperature being above 425°C. The polymers exhibited a glass‐transition temperature in the range of 195–295°C, with a reasonable interval between glass‐transition and decomposition temperature. Electrical insulating properties of some polymer films were evaluated on the basis of dielectric constant and dielectric loss and their variation with frequency and temperature. The values of the dielectric constant at 10 kHz and 20°C were in the range of 3.16–3.25. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献