The Gompertzian curve reveals fractal properties of tumor growth

The normalized Gompertzian curve reflecting growth of experimental malignant tumors in time can be fitted by the power function y(t)=at^b with the coefficient of nonlinear regression r0.95, in which the exponent b is a temporal fractal dimension, (i.e., a real number), and time t is a scalar. This curve is a fractal, (i.e., fractal dimension b exists, it changes along the time scale, the Gompertzian function is a contractable mapping of the Banach space R of the real numbers, holds the Banach theorem about the fix point, and its derivative is 1). This denotes that not only space occupied by the interacting cancer cells, but also local, intrasystemic time, in which tumor growth occurs, possesses fractal structure. The value of the mean temporal fractal dimension decreases along the curve approaching eventually integer values; a fact consistent with our hypothesis that the fractal structure is lost during tumor progression.     

A New Fluorescent Sensor Based on 1H-pyrazolo[3,4-b]quinoline Skeleton. Part 2

A novel fluorescent dye bis-(pyridin-2-yl-methyl)-(1,3,4-triphenyl-1H-pyrazolo[3,4-b]quinolin-6-ylmethyl)-amine (P1) has been synthesized and investigated by means of steady state and time-resolved fluorescence techniques. This compound acts as sensor for fluorescence detection of small inorganic cations (lithium, sodium, barium, magnesium, calcium, and zinc) in highly polar solvents such as acetonitrile. The mechanism which allows application of this compound as sensor is an electron transfer from the electron-donative part of molecule (amine) to the acceptor part (pyrazoloquinoline derivative), which is retarded upon complexation of the electro-donative part by inorganic cations. The binding constants are strongly dependent on the charge density of the analyzed cations. The 2/1 complexes of P1 with Zn(++) and Mg(++) cations posses large binding constants. Moreover, in the presence of these cations a significant bathochromic shift of fluorescence is observed. The most probable explanation of such behaviour is the formation of intramolecular excimer. This is partially supported by the quantum chemical calculations.     

Growth and EPR properties of KSm(WO4)2 and KEr(WO4)2 single crystals

Growth conditions and electron paramagnetic resonance investigations of two well oriented KSm(WO₄)₂ and KEr(WO₄)₂ single crystals have been presented and discussed. Hyperfine structure of Sm³⁺ ion was detected and analyzed for angular and temperature dependences. EPR spectra of KEr(WO₄)₂ and its angular dependence showed the presence of 5 magnetically nonequivalent Er centers in the crystal. A change in the type of magnetic interactions was analyzed using mixed (Gaussian and Lorentzian) fits of the EPR spectra.     

Vibro-acoustic method for estimating a liquid level and viscosity

The goal of this work has been to examine a possibility to measure a liquid level and its viscosity by the vibro-acoustic methods. Preliminary laboratory investigations were completed on a glass vessel filled with solutions of various viscosity and level, excited by a hammer. A microphone and four accelerometers were used as sensors. Few criteria symptoms were checked. For the level and viscosity estimation there were used the placement and values of the Fourier's spectra maximum of the acoustic signal, and of the vibration signals from sensors. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ultrashort 1.5-microm laser excited upconverted stimulated emission based on simultaneous three-photon absorption

Simultaneous three-photon excited stimulated emission at (cavityless lasing) approximately 610 nm has been achieved in an organic chromophore solution pumped by approximately 1.5-microm ultrashort coherent radiation. The stimulated emission can be observed only in the forward and backward directions and is characterized by its high directionality and spectral narrowing. The divergence angle for the backward stimulated emission is considerably smaller than that for the forward stimulated emission, which resembles optical phase conjugation.     

The Ability of Functionalized Fullerenes and Surface‐Modified TiO2 Nanoparticles to Photosensitize Peroxidation of Lipids in Selected Model Systems

Photochemical properties of a new class of inorganic nanoparticles, namely a cationic C₆₀ fullerene substituted with three quaternary pyrrolidinium groups (BB6) and a surface‐modified nanocrystalline TiO₂ with bromopyrogallol red (Brp@TiO₂) were examined for their effectiveness in photogenerating singlet oxygen and free radicals. In particular, their ability to photosensitize peroxidation of unsaturated lipids was analyzed in POPC:cholesterol liposomes and B16 mouse melanoma cells employing a range of spectroscopic and analytical methods. Because melanoma cells typically are pigmented, we examined the effect of melanin on the photosensitized peroxidation of lipids in liposomes and B16 melanoma cells, mediated by BB6 and Brp@TiO₂ nanoparticles. The obtained results suggest that peroxidation of unsaturated lipids, photosensitized by BB6 occurs mainly, although not exclusively, via Type II mechanism involving singlet oxygen. On the other hand, if surface‐modified TiO₂ is used as a photosensitizer, Type I mechanism of lipid peroxidation dominates, as indicated by the predominant formation of the free radical‐dependent cholesterol oxidation products. The protective effect of melanin was particularly evident when BB6 was used as a photosensitizer, suggesting that melanin could efficiently interfere with Type II processes.     

Electronic absorption spectra of C3Cl, C4Cl, and their ions in neon matrices

Electronic absorption spectra of C3Cl, C3Cl+, C3Cl-, C4Cl, and C4Cl+ have been recorded in 6 K neon matrices following mass selection. Ab initio calculations were performed (CCSD(T) and CASSCF) to identify the ground and accessible excited states of each molecule. The estimated excitation energies and transition moments aid the assignment. The absorptions observed for C3Cl are the 5(2)A' <-- X(2)A' and 3(2)A' <-- X(2)A' transitions of the bent isomer and the (2)A1 <-- X(2)B2 transition of the cyclic form in the UV (336.1 nm), visible (428.7 nm), and near-IR (1047 nm) regions, respectively. The band systems for bent C3Cl- (435.2 nm) and linear C3Cl+ (413.2 nm) are both in the visible region and correspond to 2(1)A' <-- X(1)A' and (1)pi <-- X(1)sigma+ type transitions. The C4Cl and C4Cl+ chains are linear, and the band origins of the 2(2)pi <-- X(2)pi and 2(3)pi <-- X(3)pi electronic transitions are at 427.0 and 405.7 nm. The spectral assignments are supported by analysis of the vibrational structure associated with each electronic transition.     

The surface tension and density of the Cu-Ag-In alloys

The surface tension and the densities of the Cu-Ag-In alloys have been measured by means of the sessile drop method. The density of these alloys depends linearly on temperature in the case of all the investigated compositions. The surface tension shows a linear dependence on temperature except for the lowest temperatures. For most of the alloys, the surface tension at the lowest temperature is lower than that predicted by the straight line. The experimental values of the surface tension of the Cu-Ag-In alloys are compared with those computed from the model, and quite good agreement is observed.