Kinetic roughening in two-phase fluid flow through a random Hele-Shaw cell

A nonlocal interface equation is derived for two-phase fluid flow, with arbitrary wettability and viscosity contrast, c=(mu(1)-mu(2))/(mu(1)+mu(2)), in a model porous medium defined as a Hele-Shaw cell with random gap b(0)+delta b. Fluctuations of both capillary and viscous pressure are explicitly related to the microscopic quenched disorder, yielding conserved, nonconserved, and power-law correlated noise terms. Two length scales are identified that control the possible scaling regimes and which scale with capillary number Ca as l(1) approximately b(0)(cCa)(-1/2) and l(2) approximately b(0)Ca-1. Exponents for forced fluid invasion are obtained from numerical simulation and compared with recent experiments.     

The synthesis of multi-walled carbon nanotubes (MWNTs) by catalytic pyrolysis of the phenol-formaldehyde resins

A series of carbon nanomaterials, particularly multi-walled carbon nanotubes (MWNT), are obtained as products from catalytic pyrolysis of the cross-linked phenol-formaldehyde resins with different ferrocene under inert atmosphere. The morphology and structure of the samples were evaluated by TEM and XRD techniques. CNTs morphology is dependent on the iron nanoparticles and their forms (Fe, Fe₃C) resulted from ferrocene decomposition. The amount of nanotubes increases with iron content released from ferrocene catalyst during the pyrolysis process. Fe₃C nanoparticles drive the nucleation and the growth of carbon nanotubes during the pyrolysis process. Long (up to microns) well-defined MWNTs with small defects, ropes and disordered carbon are representatives in the pyrolyzed resins composition.     

Statistical Approach of Modulational Instability in the Class of Derivative Nonlinear Schrödinger Equations

The modulational instability (MI) in the class of NLS equations is discussed using a statistical approach (SAMI). A kinetic equation for the two-point correlation function is studied in a linear approximation, and an integral stability equation is found. The modulational instability is associated with a positive imaginary part of the frequency. The integral equation is solved for different types of initial distributions (δ-function, Lorentzian) and the results are compared with those obtained using a deterministic approach (DAMI). The differences between MI of the normal NLS equation and derivative NLS equations is emphasized. PACS: 05.45.     

Self-assembled dimers with supramolecular chirality

The possibilities to form dimeric capsules with supramolecular chirality from tetraurea calix[4]arenes composed of two different phenolic urea units are discussed in general and demonstrated experimentally for various selected examples.     

Comparative Protective Effect of Nigella sativa Oil and Vitis vinifera Seed Oil in an Experimental Model of Isoproterenol-Induced Acute Myocardial Ischemia in Rats

The study’s aim was to characterize the composition of Nigella sativa seed (NSO) and grape seed (GSO) oils, and to evaluate their cardioprotective and anti-inflammatory effect on isoproterenol (ISO)-induced ischemia in rats. Materials and Methods: NSO and GSO supplements were physicochemically characterized. Liquid chromatography–mass spectrometry (HPLC-MS), Fourier-transform infrared spectroscopy (FTIR), and gas chromatography–mass spectrometry (GC-MS) analyses were used to determine the phytochemical composition in the oils. Total polyphenol content (TPC) and in vitro antioxidant activity were also determined. Pretreatment with 4 mL/kg/day NSO or GSO was administered to rats for 14 days. The experimental ischemia was induced by a single administration of ISO 45 mg/kg after 14 days. An electrocardiogram (ECG) was performed initially and 24 h after ISO. Biological evaluation was done at the end of experiment. Results: The HPLC-MS, GC-MS, and FTIR analyses showed that both NSO and GSO are important sources of bioactive compounds, especially catechin and phenolic acids in GSO, while NSO was enriched in flavonoids and thymol derivatives. Pretreatment with GSO and NSO significantly reduced ventricular conduction, prevented the cardiotoxic effect of ISO in ventricular myocardium, and reduced the level of proinflammatory cytokines and CK-Mb. Conclusion: Both NSO and GSO were shown to have an anti-inflammatory and cardioprotective effect in ISO-induced ischemia.     

Catalytically Active and Spectator Ce3+ in Ceria‐Supported Metal Catalysts

Identification of active species and the rate‐determining reaction steps are crucial for optimizing the performance of oxygen‐storage materials, which play an important role in catalysts lowering automotive emissions, as electrode materials for fuel cells, and as antioxidants in biomedicine. We demonstrated that active Ce³⁺ species in a ceria‐supported platinum catalyst during CO oxidation are short‐lived and therefore cannot be observed under steady‐state conditions. Using time‐resolved resonant X‐ray emission spectroscopy, we quantitatively correlated the initial rate of Ce³⁺ formation under transient conditions to the overall rate of CO oxidation under steady‐state conditions and showed that ceria reduction is a kinetically relevant step in CO oxidation, whereas a fraction of Ce³⁺ was present as spectators. This approach can be applied to various catalytic processes involving oxygen‐storage materials and reducible oxides to distinguish between redox and nonredox catalytic mechanisms.     

Direct observation of protein motion during the photochemical reaction cycle of bacteriorhodopsin

Platinum-coated, conductive atomic force microscope cantilevers were used to deposit electrophoretically purple membranes from Halobacterium salinarum on the bottom part of the cantilevers. By illuminating the bacteriorhodopsin-containing purple membranes, the protein goes through its photochemical reaction cycle, during which a conformational change happens in the protein, changing its shape and size. The size change of the protein acts upon the cantilever by causing its deflection, which can be monitored by the detection system of the atomic force microscope. The shape of the signal, the action spectrum of the deflection amplitude, and the blue light inhibition of the deflection all prove that the origin of the signal is the conformational change arising in the bacteriorhodopsin during the photocycle. From the size of the signal, the magnitude of the protein motion could be estimated. Using polarized light, the orientation of the motion was determined, relative to the transition moment of the retinal.     

Identification of Novel Antistaphylococcal Hit Compounds Targeting Sortase A

Staphylococcus aureus (S. aureus) is a causative agent of many hospital- and community-acquired infections with the tendency to develop resistance to all known antibiotics. Therefore, the development of novel antistaphylococcal agents is of urgent need. Sortase A is considered a promising molecular target for the development of antistaphylococcal agents. The main aim of this study was to identify novel sortase A inhibitors. In order to find novel antistaphylococcal agents, we performed phenotypic screening of a library containing 15512 compounds against S. aureus ATCC43300. The molecular docking of hits was performed using the DOCK program and 10 compounds were selected for in vitro enzymatic activity inhibition assay. Two inhibitors were identified, N,N-diethyl-N′-(5-nitro-2-(quinazolin-2-yl)phenyl)propane-1,3-diamine (1) and acridin-9-yl-(1H-benzoimidazol-5-yl)-amine (2), which decrease sortase A activity with IC₅₀ values of 160.3 µM and 207.01 µM, respectively. It was found that compounds 1 and 2 possess antibacterial activity toward 29 tested multidrug resistant S. aureus strains with MIC values ranging from 78.12 to 312.5 mg/L. These compounds can be used for further structural optimization and biological research.     

Higher carbene homologues: Naphtho[2,3-d]-1,3,2λ2-diazagermole, -diazastannole,and attempted reduction of 2,2-dichloronaphtho[2,3-d]-1,3,2-diazasilole

N,N′-Dineopentyl-2,3-diaminonaph-thalene 1, obtained by reaction of 2,3-diaminonaph-thalene with pivaloyl chloride and subsequent re-duction, was dilithiated and cyclodisubstituted with SiCl₄ to give dichloro-dineopentyl-naphtho[2,3-d]-1,3,2-diazasilole 2. Treatment of 2 with two equivalents of potassium in THF caused cleavage of the Si–N ring. A silylene could not be detected. The corresponding cyclic diaminogermylene 3 and diamino-stannylene 4 were obtained by direct ring closure of 1–Li₂ with GeCl₂·dioxane or SnCl₂, respectively. The compounds are structurally characterized by NMR and MS. The properties of 3 and 4 are compared with those of related germylenes and stannylenes. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:439–444, 1998