UJA-3DFD: A program to compute the 3D fractal dimension from MRI data

This work presents a computer program for computing the 3D fractal dimension (3DFD) from magnetic-resonance images of the brain. The program is based on an algorithm that calculates the 3D box counting of the entire volume of the brain, and also of its 3D skeletonization. The validity and accuracy of the software has been confirmed using solids with well-known 3DFD values. The usefulness of the program developed is demonstrated by its successful characterization of several neurodegenerative diseases.     

Extracting kinetic parameters of aniline polymerization from thermal data of a batch reactor. simulation of the thermal behavior of a reactor

A simulation model of the thermal behavior of a reactor during aniline polymerization is proposed. The model takes into account the polymerization mechanism together with heat production and dissipation. The temperature–time profiles can be simulated with different kinetic parameters. The model is used for two purposes: to extract kinetic parameters by fitting experimental temperature–time profiles of a cooled agitated batch reactor; and to estimate the temperatures changes occurring in a reactor under different experimental conditions to find the best conditions for industrial production of polyaniline. The rate equation used includes two rate constants: one in the absence of polymer (k₁) and another in the presence of polymer (k₂). The thermal factors, such as the heat transfer coefficient and the reaction enthalpy, are experimentally measured. A computer program is written that fits the experimental data using different kinetic parameters. The data analysis shows a temperature peak (T_max) whose magnitude decreases when k₂ decreases, whereas it is not affected by k₁. The time to reach the T_max is inversely proportional to k₁ and k₂. The model allows obtaining the kinetic parameters in different reaction media, e.g. varying the concentration of acid. The model is used to simulate the thermal behavior, to polymerize 1M of aniline: in one step the temperature of the reactor will increase till 82ºC, such thermal runaway will cause polymer degradation, successive additions of portions of the total oxidant amount, paced at defined time intervals, is devised to maintain low temperatures while producing the same amount of polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39409.     

Microalbuminuria in arterial hypertension

Microalbuminuria is a considerable good indicator of atherogenic disease and cardiovascular risk. In the arterial hypertension, the main centre organ is the kidney. Structural and functional changes that happen in the hypertensive nephropathy are going to cause alterations m the albumin urinary excretion. The authors have done a revision of the main factors which can origin the existence of microalbuminuria in patients with arterial hypertension, and they conclude that this is an useful biochemist indicator in order to evaluate the degree of renal disease in these patients.     

Three‐dimensional thinning algorithms on graphics processing units and multicore CPUs

Three‐dimensional curve skeletons are a very compact representation of three‐dimensional objects with many uses and applications in fields such as computer graphics, computer vision, and medical imaging. An important problem is that the calculation of the skeleton is a very time‐consuming process. Thinning is a widely used technique for calculating the curve skeleton because of the properties it ensures and the ease of implementation. In this paper, we present parallel versions of a thinning algorithm for efficient implementation in both graphics processing units and multicore CPUs. The parallel programming models used in our implementations are Compute Unified Device Architecture (CUDA) and Open Computing Language (OpenCL). The speedup achieved with the optimized parallel algorithms for the graphics processing unit achieves 106.24x against the CPU single‐process version and more than 19x over the CPU multithreaded version. Copyright © 2011 John Wiley & Sons, Ltd.     

Spectroelectrochemical study of the oxidation of diaminophenols on platinum electrodes in acidic medium

The electrochemical oxidation of 2,3- 2,4- and 2,5-diaminophenol, on platinum electrode, in acid medium was studied using cyclic voltammetry, in situ UV-vis and in situ FTIR spectroscopies. The spectroscopic data indicates that 2,4-diaminophenol suffers hydrolysis giving the formation of 2-amino-hydroquinone/2-amino-p-benzoquinone in solution. The oxidation mechanism of 2,5-diaminophenol is similar to the p-phenylenediamine giving 2-hydroxy-p-benzoquinoneimine and its hydrolysis product, 2-hydroxy-p-benzoquinone. The electrochemical results suggest that 2,3-diaminophenol generates a non-electroactive polymeric material on the electrode surface.     

Evaluation of Boolean operations between free-form solids using extended simplicial chains and PN triangles

This paper presents a method to evaluate Boolean operations between free-form solids modeled using Extended Simplicial Chains (ESCs). The ESC model is a formal system to represent not only the boundary, but also the volume of free-form solids, that allows the development of simple and robust algorithms. In this implementation of the ESC model, the free-form solids and the results of the operations are bounded by PN triangles and represented by ESCs, and the surface intersection and trimming are computed using adaptive subdivision of the patches and a point in solid test specifically designed for ESCs.     

Fabrication of an interpenetrated network of carbon nanotubes and electroactive polymers to be used in oligonucletide biosensing

Layers of multiwall carbon nanotubes (MWNT), with different thickness, are built by sequential drop coating of a MWNT-Nafion^® dispersion in ethanol onto glassy carbon substrates. The layers form a 3D conductive network towards the electrochemical reactions of soluble redox couples (Fe^3+/2+) in aqueous solutions. Digital simulation of the electrochemical response suggests that the electron transfer is controlled by finite diffusion of the redox species inside the network. It is possible to create an interpenetrated network of carbon nanotubes and electroactive polymers (poly(hydroxynaphtoquinones)) by electropolymerization in nonaqueous media, which are electroactive in aqueous and nonaqueous media. The electrochemical response, both in cyclic voltammetry (CV) and square wave voltammetry (SWV), is significantly increased. In that way, the sensitivity of sensors (e.g. DNA biosensors based on the change of electroactive polymer response upon hybridization) could be improved.     

Nanocomposite synthesis by absorption of nanoparticles into macroporous hydrogels. Building a chemomechanical actuator driven by electromagnetic radiation

Macroporous hydrogels irreversibly absorb solid nanoparticles from aqueous dispersions. A nanocomposite is made using a macroporous thermosensitive hydrogel (poly(N-isopropylacrylamide-co-(2-acrylamido-2-methyl propane sulfonic acid)) (poly(NIPAm-co-AMPS)) and conductive polymer (polyaniline, PANI) nanoparticles (PANI NPs). Macroporous gels of poly(NIPAm-co-AMPS) were made by a cryogelation technique. NPs of PANI were produced by precipitation polymerization. It is found that PANI NPs are easily absorbed into the macroporous hydrogels while conventional non-porous hydrogels do not incorporate NPs. It is shown that PANI NPs, dispersed in water, absorb NIR laser light or microwave radiation, increasing their temperature. Upon irradiation of the nanocomposite with microwaves or NIR laser light, the PANI NPs heat up and induce the phase transition of the thermosensitive hydrogel matrix and the internal solution is released. Other nano-objects, such as gold nanorods and PANI nanofibers, are also easily incorporated into the macroporous gel. The resulting nanocomposites also suffer a phase transition upon irradiation with electromagnetic waves. The results suggest that, using a thermosensitive matrix and conducting nanoparticles, mechanical/chemical actuators driven at a distance by electromagnetic radiation can be built. The sensitivity of the nanocomposite to electromagnetic radiation can be modulated by the pH, depending on the nature of the incorporated nanoparticles. Additionally, it is possible to make systems which absorb either NIR or microwaves or both.