Estabilidade do ácido fólico em suspensão oral extemporânea

Apesar do ácido fólico (AF) ser utilizado em pediatria na prevenção e tratamento de deficiências desta vitamina, não existe actualmente disponível uma forma farmacêutica adequada a doentes pediátricos, o que requer o desenvolvimento de uma preparação líquida extemporânea. A utilização segura destas preparações deve ser suportada por documentação adequada sobre estabilidade física e química. O objectivo do presente trabalho foi investigar a estabilidade do AF numa suspensão oral extemporânea 50 g/ml, preparada a partir de comprimidos disponíveis comercialmente (5 mg). A suspensão de AF foi conservada em recipientes de vidro à temperatura de 2-8 ºC e sob protecção da luz. Cinco amostras independentes foram analisadas no tempo 0 e após 1, 3, 5 e 7 dias. O teor em AF foi determinado através de um método de HPLC em fase reversa, com adequada linearidade, precisão, exactidão e selectividade. A concentração de AF foi superior a 95% em todos os tempos de amostragem e a aparência física, cor e odor da suspensão não sofreram alteração durante o período do estudo. O AF revelou ser estável em suspensão aquosa pelo menos durante 14 dias a 2-8 ºC e ao abrigo da luz, o que poderá permitir a sua utilização em doentes pediátricos.

Effect of fibre morphology on flocculation of fibre-cement suspensions

The objective of the present research was to evaluate the effect of fibre morphology (e.g., length, width, fibrillation, broken ends, content of fines and number of fibres per gram) on flocculation and drainage properties of fibre-cement suspensions and on physical properties of the fibre-cement composites. Mechanical refining was used to change the morphological properties of Eucalyptus and Pinus pulps. Results show that the mechanical refining increased the size of the formed flocs and decreased the concentration of free small particles (with dimensions between 1 and 20 pm) as a consequence of the increased fibrillation and content of fines, which increased the capacity of the fibres to capture the mineral particles. High levels of refining were necessary for Pinus pulp to obtain cement retention values similar to those obtained by unrefined Eucalyptus pulp. This is due to the higher number of fibres per gram in Eucalyptus pulp than in Pinus pulp. Pulp refining improved the packing of the particles and, although decreased the drainage rate. it contributed to a less porous structure, which improved the microstructure of the composite. (C) 2009 Elsevier Ltd. All rights reserved.

The rheological behavior and surface charging of gelcasting alumina suspensions

Aim of this work is to investigate the effect of monomers containing either carboxylate (ammonium acrylate) or acrylamide (hydroxymethylacrylamide) functional groups on the surface charging and theological behavior of alumina suspensions. The rheological behavior was investigated by changing the concentrations of dispersant (ammonium polyacrylate) and monomers in the suspensions. The zeta potential of alumina suspensions containing each of the different monomers was measured as a function of dispersant additions. The suspension theological behavior varied significantly depending on the monomer type, which could be explained in terms of repulsive forces, pH changes and additive interactions. (C) 2006 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Optical barcoding of colloidal suspensions: applications in genomics, proteomics and drug discovery

The enormous amount of information generated through sequencing of the human genome has increased demands for more economical and flexible alternatives in genomics, proteomics and drug discovery. Many companies and institutions have recognised the potential of increasing the size and complexity of chemical libraries by producing large chemical libraries on colloidal support beads. Since colloid-based compounds in a suspension are randomly located, an encoding system such as optical barcoding is required to permit rapid elucidation of the compound structures. We describe in this article innovative methods for optical barcoding of colloids for use as support beads in both combinatorial and non-combinatorial libraries. We focus in particular on the difficult problem of barcoding extremely large libraries, which if solved, will transform the manner in which genomics, proteomics and drug discovery research is currently performed.

Synthesis of optically complex core-shell colloidal suspensions: Pathways to multiplexed biological screening

The ability to generate enormous random libraries of DNA probes via split-and-mix synthesis on solid supports is an important biotechnological application of colloids that has not been fully utilized to date. To discriminate between colloid-based DNA probes each colloidal particle must be 'encoded' so it is distinguishable from all other particles. To this end, we have used novel particle synthesis strategies to produce large numbers of optically encoded particle suitable for DNA library synthesis. Multifluorescent particles with unique and reproducible optical signatures (i.e., fluorescence and light-scattering attributes) suitable for high-throughput flow cytometry have been produced. In the spectroscopic study presented here, we investigated the optical characteristics of multi-fluorescent particles that were synthesized by coating silica 'core' particles with up to six different fluorescent dye shells alternated with non-fluorescent silica 'spacer' shells. It was observed that the diameter of the particles increased by up to 20% as a result of the addition of twelve concentric shells and that there was a significant reduction in fluorescence emission intensities from inner shells as an increasing number of shells were deposited.

Application of GA3 and girdling of branches on the production of extemporaneous fruits of 'Tahiti' acid lime

The objective of this study was to evaluate the effect of girdling of branches and the application of GA3, still in the main crop flowering on the formation of reproductive structures, the fruit set of the following extemporaneous flowering of 'Tahiti' acid lime. This work used a randomized block design with five replications in a 4x3 factorial design. The first factor was the foliar application of GA3, 88 days before extemporaneous flowering at five concentrations (0, 7, 14 and 21 mg.L-1). The second factor was the girdling times, 108 days before flowering onset (A108AF), 78 days before flowering (A78AF) plus no-girdling control (NG). In extemporaneous flowering, the proportion of buds, flowers and fruits that abscised was 38.75, 31.25 and 18.64% respectively and 11.34% of all reproductive structures formed were collected. GA3 did not affect fruit set. Girdling increased fruit set by 229 and 256% at A108DAF and A78DAF respectively, in relation to NG plants. The GA3 reduced the formation of floral structures, which resulted in a quadratic increase in field production by reducing the competition for photoassimilates among fruits. The concentration of 21 mg.L-1 was the most productive, with 15.97 fruit.plant-1.

Investigation on the homogeneity and stability of aqueous nano cellulose suspensions prepared using pluronic F-127

This paper presents the results of experimental investigation on the aqueous dispersion behaviour of micro crystalline cellulose (MCC) prepared using Pluronic F-127. For this purpose, different concentrations (0.5-3.0 wt.%) of MCC were dispersed in water with the help of ultrasonication technique using various concentrations of Pluronic F-127. The homogeneity of the suspensions and agglomerations were characterized by optical and transmission electron microscopy and the concentration of well dispersed MCC was measured using UV-Vis spectroscopy. Also, the suspensions were subjected to high speed ultracentrifugation at 3000 rpm and observed visually for sedimentation and subsequently, concentration was calculated using UV-Vis, in order to assess the long term stability of the suspensions. Based on these experiments, optimum concentration of Pluronic to disperse different MCC concentrations has been suggested.

Particle transport in fouling caused by kaolin-water suspensions on copper tubes

Particulate fouling tests were carried out using kaolin-water suspensions flowing through an annular heat exchanger with a copper inner tube. The flow rate was changed from test to test, but the fluid temperature and pH, as well as the particle concentration, were maintained constant. In the lower range of fluid velocities (<0.5 m/s), the deposition process seemed to be controlled by mass transfer. The corresponding experimental transport fluxes were compared to the predictions obtained with several models, showing that diffusion governed particle transport. The absolute values of the mass transfer fluxes and their dependences on the Reynolds number were satisfactorily predicted by some of the models.

Disseny d’un electro-filtre a pressió a escala de laboratori per filtrar suspensions sòlid-líquid

La idea principal d’aquest projecte és dissenyar i muntar un electro-filtre a pressió, per tal d’observar si aquesta nova tècnica provoca uns majors rendiments (reducció del temps de filtració i disminució del % d’aigua en el tortó format) respecte la filtració a pressió tradicional emprada en la indústria

Light scattering from suspensions under external gradients

We analyze the light-scattering spectrum of a suspension in a viscoelastic fluid under density and velocity gradients. When a density gradient is present, the dynamic structure factor exhibits universality in the sense that its expression depends only on the reduced frequency and the reduced density gradient. For a velocity gradient, however, the universality breaks down. In this last case we have found a transition point from one to three characteristic frequencies in the spectrum, which is governed by the value of the external gradient. The presence of the viscoelastic time scales introduces a shift in the ``critical¿¿ point.

Relaxation dynamics in suspensions of ferromagnetic particles

We have studied the relaxation dynamics of a dilute assembly of ferromagnetic particles in suspension. A formalism based on the Smoluchowski equation, describing the evolution of the probability density for the directions of the magnetic moment and of the axis of easy magnetization of the particles, has been developed. We compute the rotational viscosity from a Green-Kubo formula and give an expression for the relaxation time of the particles which comes from the dynamic equations of the correlation functions. Concerning the relaxation time for the particles, our results agree quite well with experiments performed on different samples of ferromagnetic particles for which the magnetic energy, associated with the interaction between the magnetic moments and the external field, or the energy of anisotropy plays a dominant role.

Short-time dynamics of colloidal suspensions in confined geometries

We analyze the short-time dynamical behavior of a colloidal suspension in a confined geometry. We analyze the relevant dynamical response of the solvent, and derive the temporal behavior of the velocity autocorrelation function, which exhibits an asymptotic negative algebraic decay. We are able to compare quantitatively with theoretical expressions, and analyze the effects of confinement on the diffusive behavior of the suspension.

The effect of mountain bike suspensions on vibrations and off-road uphill performance.

AIM: This study evaluates the effect of front suspension (FS) and dual suspension (DS) mountain-bike on performance and vibrations during off-road uphill riding. METHODS: Thirteen male cyclists (27+/-5 years, 70+/-6 kg, VO(2max)59+/-6 mL.kg(-1).min(-1), mean+/-SD) performed, in a random sequence, at their lactate threshold, an off-road uphill course (1.69 km, 212 m elevation gain) with both type of bicycles. Variable measured: a) VO(2) consumption (K4b2 analyzer, Cosmed), b) power output (SRM) c) gain in altitude and d) 3-D accelerations under the saddle and at the wheel (Physilog, EPFL, Switzerland). Power spectral analy- sis (Fourier) was performed from the vertical acceleration data. RESULTS: Respectively for the FS and DS mountain bike: speed amounted to 7.5+/-0.7 km.h(-1) and 7.4+/-0.8 km.h(-1), (NS), energy expenditure 1.39+/-0.16 kW and 1.38+/-0.18, (NS), gross efficiency 0.161+/-0.013 and 0.159+/-0.013, (NS), peak frequency of vibration under the saddle 4.78+/-2.85 Hz and 2.27+/-0.2 Hz (P<0.01) and median-frequency of vertical displacements of the saddle 9.41+/-1.47 Hz and 5.78+/-2.27 Hz (P<0.01). CONCLUSION: Vibrations at the saddle level of the DS bike are of low frequencies whereas those of the FS bike are mostly of high frequencies. In the DS bike, the torque produced by the cyclist at the pedal level may generate low frequency vibrations. We conclude that the DS bike absorbs more high frequency vibrations, is more comfortable and performs as well as the FS bicycle.

Spontaneous aggregation and global polar ordering in squirmer suspensions

We have developed numerical simulations of three dimensional suspensions of active particles to characterize the capabilities of the hydrodynamic stresses induced by active swimmers to promote global order and emergent structures in active suspensions. We have considered squirmer suspensions embedded in a fluid modeled under a Lattice Boltzmann scheme. We have found that active stresses play a central role to decorrelate the collective motion of squirmers and that contractile squirmers develop significant aggregates.

L’eficàcia de les suspensions judicials amb obligació de tractament de deshabituació. Factors que poden influir en la reducció o no de reincidència

Aquesta recerca està motivada per l’interès en les Mesures Penals Alternatives, concretament, en les suspensions judicials com a mesura més adient per a determinats subjectes amb perfils toxicològics i que requereixen d’una intervenció que es pot abordar en context comunitari. Per tal de valorar la seva eficàcia, l’equip d’investigadors s’ha centrat en els índexs de reincidència i aquells factors que poden influir a partir de l’anàlisi estadística d’una mostra de 237 subjectes sotmesos a l’obligació de tractament de deshabituació. Observant l’índex de reincidència, en funció de l’anàlisi de variables sociopersonals i judicials dels subjectes, es busquen aquells indicadors que poden ser eficaços per reduir la comissió de nous fets delictius. Del resultats obtinguts, es conclou que variables com una bona adherència familiar, una estabilitat laboral així com la finalització correcta d’un tractament de deshabituació aporten uns nivells de reincidència baixos. Igualment, es justifica l’atorgament de suspensions judicials com a eina punitiva més eficaç per a aquells subjectes amb característiques toxicològiques i necessitats rehabilitadores a causa de la seva addicció, atès que els nivells de reincidència obtinguts en aquesta recerca aporten uns índexs més baixos que els nivells actuals de reincidència penitenciària (cal tenir en compte, però, la diferència de perfils). Es conclou que aquestes mesures penals alternatives són una eina més integradora ja que es desenvolupen en l’entorn comunitari.