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41.
Vegso K Siffalovic P Majkova E Jergel M Benkovicova M Kocsis T Weis M Luby S Nygård K Konovalov O 《Langmuir : the ACS journal of surfaces and colloids》2012,28(28):10409-10414
We report on an in-situ observation of the colloidal silver nanoparticle self-assembly into a close-packed monolayer at the air/water interface followed by a 2D to 3D transition. Using the fast tracking GISAXS technique, we were able to observe the immediate response to the compression of the self-assembled nanoparticle layer at the air/water interface and to identify all relevant intermediate stages including those far from the equilibrium. In particular, a new nonequilibrium phase before the monolayer collapse via the 2D to 3D transition was found that is inaccessible by the competing direct space imaging techniques such as the scanning and transmission electron microscopies due to the high water vapor pressure and surface tension. 相似文献
42.
Sarra Bouchelaghem Sourav Das Romen Singh Naorem Lilla Czuni Gbor Papp Marianna Kocsis 《Molecules (Basel, Switzerland)》2022,27(2)
Propolis is a natural bee product that is widely used in folk medicine. This study aimed to evaluate the antimicrobial and antibiofilm activities of ethanolic extract of propolis (EEP) on methicillin-resistant and sensitive Staphylococcus aureus (MRSA and MSSA). Propolis samples were collected from six regions in Hungary. The minimum inhibitory concentrations (MIC) values and the interaction of EEP-antibiotics were evaluated by the broth microdilution and the chequerboard broth microdilution methods, respectively. The effect of EEP on biofilm formation and eradication was estimated by crystal violet assay. Resazurin/propidium iodide dyes were applied for simultaneous quantification of cellular metabolic activities and dead cells in mature biofilms. The EEP1 sample showed the highest phenolic and flavonoid contents. The EEP1 successfully prevented the growth of planktonic cells of S. aureus (MIC value = 50 µg/mL). Synergistic interactions were shown after the co-exposition to EEP1 and vancomycin at 108 CFU/mL. The EEP1 effectively inhibited the biofilm formation and caused significant degradation of mature biofilms (50–200 µg/mL), as a consequence of the considerable decrement of metabolic activity. The EEP acts effectively as an antimicrobial and antibiofilm agent on S. aureus. Moreover, the simultaneous application of EEP and vancomycin could enhance their effect against MRSA infection. 相似文献
43.
Stretching experiments on single DNA molecules indicate that, counterintuitive to expectations, DNA overwinds when stretched and, at large forces, undergoes a transition into an overstretched form indicated by a plateau on the force–displacement diagrams. It is believed that these effects are the result of non-linearities in the elastic response of DNA. We use a discrete, base pair level model to simulate the behavior of short DNA molecules, taking into account the sequence dependent physical properties of DNA alongside with the coupling between the kinematical step parameters, yet retaining the quadratic form of local elastic energy function. By constructing bifurcation diagrams of equilibrium configurations and studying the dependence on base pair combinations we show that the quadratic model is capable of explaining the overtwisting as a result of coupling between modes of deformation and overstretching as a result of shear instability. 相似文献
44.
Structure of copolymers of p-methyl-p′-acryloyloxy azoxybenzene (MAAB) with cholesterylvinyl succinate (CVS) was studied by small- and wide-angle X-ray diffractometry, DSC, polarizing microscopy, and thermomechanical methods. The copolymers were found to be anisotropic non-crystalline substances in which the radial distribution of the radius of gyration of inhomogeneities corresponds to that of the diameter of the molecules determined by GPC. Both phase transition temperatures and clearing points of copolymers show a minimum as functions of the composition. On both sides of this minimum, the copolymers have different structures. At higher MAAB contents, the copolymer structure is similar to that of polyMAAB; at lower MAAB concentrations, alternating copolymer is formed similar in structure to polyCVS. For identification of the structures, copolymer/comonomer phase diagrams were also investigated. 相似文献
45.
Edit Urbán A. Bóta B. Kocsis K. Lohner 《Journal of Thermal Analysis and Calorimetry》2005,82(2):463-469
Summary The concentration dependent effects of deep rough mutant lipopolysaccharide (LPS) from Salmonella minnesota (R595) on two different phospholipid model membranes was investigated by differential scanning calorimetry and small-angle
X-ray scattering (SAXS). At low concentrations of LPS the well ordered multilamellar arrangement of dipalmitoylphosphatidylcholine
(DPPC) vesicles is strongly distorted resulting in a loss of positional correlation of the lipid lamellae and smaller domain
sizes within the lamellae. The pre-transition of DPPC was abolished at a LPS/DPPC molar ratio of 0.1:1 and the main or chain
melting transition was strongly broadened. Moreover, the enthalpy was significantly decreased and a transition was hardly
detected at an equimolar mixture of LPS/DPPC. LPS also affected the lamellar arrangement of a mixture of dipalmitoylphosphatidylethanolamine
(DPPE) and dipalmitoylphosphatidylglycerol (DPPG). Furthermore, a phase separation was observed for this phospholipid mixture
resulting in DPPE enriched and depleted domains. Similarly to DPPC, only a weak phase transition was observed at the highest
LPS concentration used (LPS/DPPE-DPPG 1:1 mol/mol). SAXS measurements showed that for both systems increasing the concentration
of LPS resulted in a concomitant increase of the formation of cubic structures, which are predominant at an equimolar mixture
of LPS/phospholipid. However, because of the small number of peaks it was not possible to unambiguously identify the space
group of the cubic structure, complicated by the coexistence with a lamellar phase, which was particularly detectable for
the LPS/DPPC mixture. 相似文献
46.
This paper addresses the use of different slotted pores in rotating membrane emulsification technology.Pores of square and rectangular shapes were studied to understand the effect of aspect ratio (1-3.5) and their orientation on oil droplet formation.Increasing the membrane rotation speed decreased the droplet size,and the oil droplets produced were more uniform using slotted pores as compared to circular geometry.At a given rotation speed,the droplet size was mainly determined by the pore size and the fluid velocity of oil through the pore (pore fluid velocity).The ratio of droplet diameter to the equivalent diameter of the slotted pore increased with the pore fluid velocity.At a given pore fluid velocity and rotation speed,pore orientation significantly influences the droplet formation rate: horizontally disposed pores (with their longer side perpendicular to the membrane axis) generate droplets at double the rate of vertically disposed pores.This work indicates practical benefits in the use of slotted membranes over conventional methods. 相似文献
47.
The adsorption of water vapour on anion-exchangers of various degrees of cross-linking ( x 2, x 4, x 8, x 10) and in different ionic forms (Cl(-), Br(-), I(-)) was studied by the isopiestic technique. The calculated integral free-energy changes were independent of the degree of cross-linking of the resins. With increase in the number of adsorbed water molecules the free-energy functions approached limiting values which were characteristic for the counter-ions. The free-energy change was combined with the enthalpy of water sorption (obtained from direct calorimetric measurements) to obtain the entropy change due to the water uptake. Both the enthalpy and the entropy functions indicated the existence of several processes during the adsorption of water, among which the most relevant are hydration, swelling of the matrix, and dilution of the internal electrolyte of the ion-exchanger. 相似文献
48.
J. Frei C. Ganter D. Kgi K. Kocsis M. Miljkovi A. Siewinski R. Wenger K. Schaffner O. Jeger 《Helvetica chimica acta》1966,49(3):1049-1105
The photo-induced formation of ketonic and phenolic isomers from O-acetyl-1-dehydro-testosterone ( 1a ) and from its 4-methyl homologue 1d in dioxane solution has been described earlier [8][9][13]. The present paper summarizes the findings which resulted in the course of further investigations, and which, in part, have been published in preliminary form [11][14] and in recent reviews [12]. This work includes the ultraviolet irradiation of dienone 1a , its 10α-stereoisomer 2a , and its 1-, 2- and 4-methyl homologues 1b – d . A series of rearrangements occurred in each case, as shown in Charts 2, 3, and 19. 相似文献
49.
Krishnakumar V Nagalakshmi R Manohar S Kocsis L 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(2):471-479
L-Lysine monohydrochloride dihydrate (LLMHCl), a semiorganic potential nonlinear optically active crystal possessing large hyperpolarizability and which belongs to noncentrosymmetry class has been grown and studied. The XRD analysis shows that it belongs to the auspicious symmetric space group P2(1) with two molecules in the asymmetric unit. FTIR and FT Raman of the title crystal have been studied at room temperature. The polarization light and oriented single crystals are used to assign the lines observed in the Raman spectra of the studied material. The vibrational spectral characterization has been carried out and interpreted in the light of crystal structure data and factor group analysis. The second harmonic generation (SHG) measurements have allowed identifying the C2 space group symmetry of the compound corroborating very good propensity for green emission. The optical and mechanical responses have been studied with respect to UV visible and Vickers microhardness measurements. 相似文献
50.
P. T. Lang J. Hobirk L. D. Horton A. Kallenbach M. Maraschek V. Mertens R. Neu J. Neuhauser T. Putterich W. Schneider A. C. C. Sips W. Suttrop J. Bucalossi L. Fattorini M. E. Manso K. Gal S. Kalvin G. Kocsis G. Veres J. Lister Y. Martin 《Czechoslovak Journal of Physics》2005,55(12):1557-1567
Empirical estimates indicate that the transient divertor power load induced by type-I ELMs in the standard H-mode ITER scenario
might result in intolerably short target life times. Significant experimental effort has been put on the exploration of recipes
to avoid or at least mitigate the ELM size by external intervention. Experimental ELM mitigation studies (and related modeling)
are of interest from different points of views. First, the active intervention gives access to new, externally controlled
ELMy discharge scenarios and ELM diagnostic techniques. Second, the ELM response on the type and amplitude of the applied
perturbation provides additional hints on the ELM stability. Third, mitigated ELMs, possibly different from spontaneous ones,
and their scaling are of interest ‘per se’, in case that mitigation is to be finally applied in ITER. In this contribution
we report on ELM mitigation results in ASDEX Upgrade, where we further restrict the scope to those methods involving 3D, local
non-axisymmetric perturbations.
Perturbations applied were cryogenic pellet injection, localized supersonic pulsed injection of D gas and laser blow of from
targets carrying C or Al micro pellets. The corresponding perturbations differ strongly both in the space and time domain
and provide an instrument to probe the local stability. Varying the parameters of the external perturbations by e.g. changing
the amount of injected material or the injection speed we mapped out the ELM trigger threshold with high spatial and temporal
resolutions.
Presented at the Workshop “Electric Fields, Structures and Relaxation in Edge Plasmas”, Tarragona, Spain, July 3–4, 2005. 相似文献