Wettability and ζ potentials of a series of methacrylate polymers and copolymers

Polymers and copolymers of different methacrylates were synthesized and coated on glass slides. The surfaces of the polymer films were characterized by their water contact angles and potentials using the Wilhelmy plate technique and streaming potential measurements, respectively. From contact-angle measurements information was also obtained about mobility of surface polymer chains. Receding contact angles of methyl methacrylate (MMA) copolymers containing hydrophilic or charged units were decreased as compared to the MMA homopolymer. When charged hydroxyethyl methacrylate (HEMA) copolymers were compared with the HEMA homopolymer, the advancing contact angles increased, probably due to reorientation of surface polymer chains. The receding contact angles of poly(alkyl methacrylates) first increased and then decreased with increasing side-chain lengths. These changes were related to the mobility of the different polymers. Incorporation of positively or negatively charged groups in MMA or HEMA polymers accordingly changed the potential of the polymers

Nonextensive Statistical Mechanics Application to Vibrational Dynamics of Protein Folding

The vibrational dynamics of protein folding is analyzed in the framework of Tsallis thermostatistics. The generalized partition functions, internal energies, free energies and temperature factor (or Debye-Waller factor) are calculated. It has also been observed that the temperature factor is dependent on the non-extensive parameter q which behaves like a scale parameter in the harmonic oscillator model. As $q\to 1$, we also show that these approximations agree with the result of Gaussian network model.Comment: 8 pages, 2 figure

Radiation recoil from highly distorted black holes

We present results from numerical evolutions of single black holes distorted by axisymmetric, but equatorially asymmetric, gravitational (Brill) waves. Net radiated energies, apparent horizon embeddings, and recoil velocities are shown for a range of Brill wave parameters, including both even and odd parity distortions of Schwarzschild black holes. We find that a wave packet initially concentrated on the black hole throat, a likely model also for highly asymmetric stellar collapse and late stage binary mergers, can generate a maximum recoil velocity of about 150 (23) km/sec for even (odd) parity perturbations, significantly less than that required to eject black holes from galactic cores.Comment: 15 pages, 8 figure

Anatomical Features Of The Urethra And Urinary Bladder Catheterization In Female Mice And Rats. An Essential Translational Tool [características Anatômicas Da Cateterização Da Uretra E Bexiga De Camundongos E Ratos Fêmeas. Instrumento Essencial Na Pesquisa Pré Clínica]

PURPOSE: To present fundamental anatomical aspects and technical skills necessary to urethra and urinary bladder catheterization in female mice and rats. METHODS: Urethral and bladder catheterization has been widely utilized for carcinogenesis and cancer research and still remains very useful in several applications: from toxicological purposes as well as inflammatory and infectious conditions to functional aspects as bladder dynamics and vesicoureteral reflux, among many others. RESULTS: Animal models are in the center of translational research and those involving rodents are the most important nowadays due to several advantages including human reproducibility, easy handling and low cost. CONCLUSIONS: Although technical and anatomical pearls for rodent urethral and bladder access are presented as tackles to the advancement of lower urinary tract preclinical investigation in a broaden sight, restriction to female animals hampers the male microenvironment, demanding future advances.26SUPPL. 2106110Reis, L.O., Fávaro, W.J., Ferreira, U., Billis, A., Fazuoli, M.G., Cagnon, V.H., Evolution on experimental animal model for upper urothelium carcinogenesis (2010) World J Urol, 28, pp. 499-505Mulder, G.J., Scholtens, E., Meijer, D.K., Collection of metabolites in bile and urine from the rat (1981) Methods Enzymol, 77, pp. 21-30Krinke, G.J., (2000) The Laboratory Rat, , San Diego, CA: Academic PressPhillips, J.I., Davies, I., The comparative morphology of the bladder and urethra in young and old female C57BL/Icrfat mice (1980) Exp Geront, 15, pp. 551-562Andersson, K.E., Arner, A., Urinary bladder contraction and relaxation: Physiology and pathophysiology (2004) Physiol Rev, 84, pp. 935-986Reis, L.O., Pereira, T.C., Favaro, W.J., Cagnon, V.H., Lopes-Cendes, I., Ferreira, U., Experimental animal model and RNA interference: A promising association for bladder cancer research (2009) World J Urol, 27, pp. 353-361Marini, R.P., Esteves, M.I., Fox, J.G., A technique for catheterization of the urinary bladder in the ferret (1994) Lab Anim, 28, pp. 155-15

Estimation of loan portfolio risk on the basis of Markov chain model

A change of shares of credits portfolio is described by Markov chain with discrete time. A credit state is determined on as an accessory to some group of credits depending on presence of indebtedness and its terms. We use a model with discrete time and fix the system state through identical time intervals - once a month. It is obvious that the matrix of transitive probabilities is known incompletely. Various approaches to the matrix estimation are studied and methods of forecast the portfolio risk are proposed. The portfolio risk is set as a share of problematic loans. We propose a method to calculate necessary reserves on the base of the considered model. © 2013 IFIP International Federation for Information Processing.German Sci. Found. (DFG) Eur. Sci. Found. (ESF);Natl. Inst. Res. Comput. Sci. Control France (INRIA);DFG Research Center MATHEON;Weierstrass Institute for Applied Analysis and Stochastics (WIAS);European Patent Offic

Gravitational Energy of Kerr and Kerr Anti-de Sitter Space-times in the Teleparallel Geometry

In the context of the Hamiltonian formulation of the teleparallel equivalent of general relativity we compute the gravitational energy of Kerr and Kerr Anti-de Sitter (Kerr-AdS) space-times. The present calculation is carried out by means of an expression for the energy of the gravitational field that naturally arises from the integral form of the constraint equations of the formalism. In each case, the energy is exactly computed for finite and arbitrary spacelike two-spheres, without any restriction on the metric parameters. In particular, we evaluate the energy at the outer event horizon of the black holes.Comment: 11 pages, 1 figure, to appear in JHEP11(2003)00

Black hole thermodynamical entropy

As early as 1902, Gibbs pointed out that systems whose partition function diverges, e.g. gravitation, lie outside the validity of the Boltzmann-Gibbs (BG) theory. Consistently, since the pioneering Bekenstein-Hawking results, physically meaningful evidence (e.g., the holographic principle) has accumulated that the BG entropy $S_{BG}$ of a $(3+1)$ black hole is proportional to its area $L^2$ ($L$ being a characteristic linear length), and not to its volume $L^3$. Similarly it exists the \emph{area law}, so named because, for a wide class of strongly quantum-entangled $d$-dimensional systems, $S_{BG}$ is proportional to $\ln L$ if $d=1$, and to $L^{d-1}$ if $d>1$, instead of being proportional to $L^d$ ($d \ge 1$). These results violate the extensivity of the thermodynamical entropy of a $d$-dimensional system. This thermodynamical inconsistency disappears if we realize that the thermodynamical entropy of such nonstandard systems is \emph{not} to be identified with the BG {\it additive} entropy but with appropriately generalized {\it nonadditive} entropies. Indeed, the celebrated usefulness of the BG entropy is founded on hypothesis such as relatively weak probabilistic correlations (and their connections to ergodicity, which by no means can be assumed as a general rule of nature). Here we introduce a generalized entropy which, for the Schwarzschild black hole and the area law, can solve the thermodynamic puzzle.Comment: 7 pages, 2 figures. Accepted for publication in EPJ

Decomposition and nutrient release of leguminous plants in coffee agroforestry systems.

Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and(lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants

Green manure in coffee systems in the region of Zona da Mata, Minas Gerais: characteristics and kinetics of carbon and nitrogen mineralization.

The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis)to produce above-ground biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation.C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by the altitude and position of the area relative to the sun