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41.
Simona Somacescu Viorica Parvulescu Jose Maria Calderon-Moreno Soong-Hyuck Suh Petre Osiceanu Bao-Lian Su 《Journal of nanoparticle research》2012,14(6):1-17
The design of cell-based bioreactors for inorganic particles formation requires both a better understanding of the underlying processes and the identification of most suitable organisms. With this purpose, the process of Au3+ incorporation, intracellular reduction, and Au0 nanoparticle release in the culture medium was compared for four photosynthetic microorganisms, Klebsormidium flaccidum and Cosmarium impressulum green algae, Euglena gracilis euglenoid and Anabaena flos-aquae cyanobacteria. At low gold content, the two green algae show maintained photosynthetic activity and recovered particles (ca. 10?nm in size) are similar to internal colloids, indicating a full biological control over the whole process. In similar conditions, the euglenoid exhibits a rapid loss of biological activity, due to the absence of protective extracellular polysaccharide, but could grow again after an adaptation period. This results in a larger particle size dispersity but larger reduction yield. The cyanobacteria undergo rapid cell death, due to their prokaryotic nature, leading to high gold incorporation rate but poor control over released particle size. Similar observations can be made after addition of a larger gold salt concentration when all organisms rapidly die, suggesting that part of the process is not under biological control anymore but also involves extracellular chemical reactions. Overall, fruitful information on the whole biocrystallogenesis process is gained and most suitable species for further bioreactor design can be identified, i.e., green algae with external coating. 相似文献
42.
43.
Bew SP Burrows AD Düren T Mahon MF Moghadam PZ Sebestyen VM Thurston S 《Chemical communications (Cambridge, England)》2012,48(40):4824-4826
An upper rim-functionalised calix[4]arene dicarboxylic acid (H(2)caldc) has been used to prepare four metal-organic frameworks, three of which have been structurally characterised and shown to form two- or three-dimensional network structures. Simulations suggest that such networks are likely to display interesting selectivity to guest molecules. 相似文献
44.
Anton Stefanescu Massimiliano Ferrara Maria Viorica Stefanescu 《Journal of Optimization Theory and Applications》2012,155(3):1060-1072
Equilibrium in choice is a solution-concept for noncooperative games defined in a general framework??the game in choice form. There are two leading ideas of the new definition. One is that the players?? preferences need not be explicitly represented, but earlier accepted solution concepts should be formally derived as particular cases. Secondly, the choice of a player need not be a best reply to the strategy combination of the others, if the choices of the other players are motivated for themselves and a best reply does not exist. It is shown that in the present framework are included classical models of game theory, and the new concept extends various known noncooperative solutions. The main technical results of the paper concern the existence of the equilibrium in choice. As particular cases, known results on the existence of classical solutions are found. Thus, our approach can be also seen as a general method for proving the existence of different solutions for noncooperative games. 相似文献
45.
Oana Ursache Constantin Gaina Viorica Gaina Nita Tudorachi Alexandra Bargan Cristian-Dragos Varganici Dan Rosu 《Journal of Thermal Analysis and Calorimetry》2014,118(3):1471-1481
Thermoreversible networks obtained by the Diels–Alder cycloaddition reaction of poly(vinyl furfural) with urethane bismaleimides containing polyether chain were synthesized. The formation of the networks was confirmed by attenuated total reflectance in conjunction with Fourier transform infrared spectroscopy (ATR–FTIR). The materials thermal properties were investigated using differential scanning calorimetry (DSC) and a coupling of dynamic thermogravimetry with Fourier transform infrared spectroscopy and mass spectrometry (TG–FTIR–MS) for pyrolysis behaviour under nitrogen atmosphere. A thermal decomposition mechanism of the networks and poly(vinyl furfural) was discussed via evolved gas analysis. The thermoreversibility of the networks was demonstrated by the presence of the endothermic peak characteristic to the retrodienic process on the DSC heating curves and also the appearance of the exothermic peak, due to the dienic process, on the DSC cooling curve. The dynamic contact angle and free surface energy values of the networks were determined. Measures of the heterogeneity and roughness of the surfaces suggested that the surfaces of the networks’ films are more homogenous than the initial poly(vinyl furfural) surface. Dynamic water vapour sorption studies were conducted. 相似文献
46.
Anna I. Arkhypchuk Dr. Andreas Orthaber Viorica Alina Mihali Dr. Andreas Ehlers Prof. Koop Lammertsma Dr. Sascha Ott 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(41):13692-13704
The reaction of a {W(CO)5}‐stabilized phosphinophosphonate 1 , (CO)5WPH(Ph)? P(O)(OEt)2, with ethynyl‐ ( 2 a – f ) and diethynylketones ( 7 – 11 , 18 , and 19 ) in the presence of lithium diisopropylamide (LDA) is examined. Lithiated 1 undergoes nucleophilic attack in the Michael position of the acetylenic ketones, as long as this position is not sterically encumbered by bulky (iPr)3Si substituents. Reaction of all other monoacetylenic ketones with lithiated 1 results in the formation of 2,5‐dihydro‐1,2‐oxaphospholes 3 and 4 . When diacetylenic ketones are employed in the reaction, two very different product types can be isolated. If at least one (Me)3Si or (Et)3Si acetylene terminus is present, as in 7 , 8 , and 19 , an anionic oxaphosphole intermediate can react further with a second equivalent of ketone to give cumulene‐decorated oxaphospholes 14 , 15 , 24 , and 25 . Diacetylenic ketones 10 and 11 , with two aromatic acetylene substituents, react with lithitated 1 to form exclusively ethenyl‐bridged bisphospholes 16 and 17 . Mechanisms that rationalize the formation of all heterocycles are presented and are supported by DFT calculations. Computational studies suggest that thermodynamic, as well as kinetic, considerations dictate the observed reactivity. The calculated reaction pathways reveal a number of almost isoenergetic intermediates that follow after ring opening of the initially formed oxadiphosphetane. Bisphosphole formation through a carbene intermediate G is greatly favored in the presence of phenyl substituents, whereas the formation of cumulene‐decorated oxaphospholes is more exothermic for the trimethylsilyl‐containing substrates. The pathway to the latter compounds contains a 1,3‐shift of the group that stems from the acetylene terminus of the ketone substrates. For silyl substituents, the 1,3‐shift proceeds along a smooth potential energy surface through a transition state that is characterized by a pentacoordinated silicon center. In contrast, a high‐lying transition state TS(E′–F′)R=Ph of 37 kcal mol?1 is found when the substituent is a phenyl group, thus explaining the experimental observation that aryl‐terminated diethynylketones 10 and 11 exclusively form bisphospholes 16 and 17 . 相似文献
47.
Email: vio{at}utgjiu.ro
Received on September 12, 2007; Accepted on December 26, 2008 In this article, we discuss a quadratic control problem forlinear discrete-time systems with Markov perturbations in Hilbertspaces, which is linked to a discrete-time Riccati equationdefined on certain infinite-dimensional ordered Banach space.We prove that under stabilizability and stochastic uniform observabilityconditions, the Riccati equation has a unique, uniformly positive,bounded on N and stabilizing solution. Based on this result,we solve the proposed optimal control problem. An example illustratesthe theory. 相似文献
48.
Salceanu Daniela-Crina Pincu Elena Bruni Giovanna Marini Amedeo Meltzer Viorica 《Journal of Thermal Analysis and Calorimetry》2018,132(2):1095-1103
Journal of Thermal Analysis and Calorimetry - The physico-chemical characterization of norfloxacin commercial sample (NF), norfloxacin anhydrous form A (NFanhA), norfloxacin pentahydrate... 相似文献
49.
Ewelina Maślak Wojciech Kupczyk Viorica Railean Paweł Pomastowski Marek Jackowski Bogusław Buszewski 《Electrophoresis》2022,43(20):2005-2013
One of the challenges medicine faces is the constantly growing resistance of pathogens to various classes of antibiotics. In this study, we investigated the use of capillary electrophoresis (CE) to characterize and assess the physiological states of three clinical bacterial strains—methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA), and Escherichia coli extended-spectrum β-lactamases (ESβL)—exposed to different antibiotics. All chosen bacteria are the leading causes of healthcare-associated and hospital-acquired invasive infections in adults. In the first part of the research, it was determined the optimal incubation time of the tested strains with antibiotics, represented as an optimal time of 24 h. In the second part, we have compared two approaches: flow cytometry (FC) as a standard method and CE as a proposed alternative approach. The viability of clinical strains treated with different class antibiotics calculated in CE measurements was strongly correlated (>0.83 for MSSA, >0.92 for ESβL and MRSA) with the viability obtained on the basis of FC measurements. As a result, CE has a chance to become a modern diagnostic method used in clinical practice. The CE cutoff was found to be 50%; above this value, the strain shows resistance to the action of the antibiotic. 相似文献
50.
Gabriel-Dnu Mocanu Oana-Viorela Nistor Oana Emilia Constantin Doina Georgeta Andronoiu Viorica Vasilica Barbu Elisabeta Botez 《Molecules (Basel, Switzerland)》2022,27(5)
Green pickled tomatoes are a traditional fermented product in Romania. This study was focused on the effect of total substitution of NaCl with KCl and MgCl2 on physicochemical and microbiological quality; bioactive compounds; and microstructural, textural, and sensorial properties of fresh and pickled green tomatoes during 28 days of fermentation. By the means of physicochemical composition, the NaCl addition induced the most stable characteristics for the pickles compared to the other two types of salts. The content of total flavonoids in green pickled tomatoes with NaCl (34.72 ± 0.43 mg CE/g DW) was significantly lower compared with the control sample (63.80 ± 0.55 mg CE/g DW). The total number of lactic acid bacteria (LAB) at the final stage of fermentation varied between 4.11 and 4.63 log CFU for all variants. The textural analysis revealed that the NaCl has the lowest influence on the textural parameters. Finally, the overall acceptance of green pickled tomatoes containing KCl and MgCl2 was found to be proper to be consumed as a substitute for pickles with NaCl. 相似文献