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.

Adsorption of colloidal particles in the presence of external fields

We present a new class of sequential adsorption models in which the adsorbing particles reach the surface following an inclined direction (shadow models). Capillary electrophoresis, adsorption in the presence of a shear, and adsorption on an inclined substrate are physical manifestations of these models. Numerical simulations are carried out to show how the new adsorption mechanisms are responsible for the formation of more ordered adsorbed layers and have important implications in the kinetics, in particular, modifying the jamming limit.

Photonic characteristics of Langmuir-Blodgett self-assembled monolayers of colloidal silica particles

Monodispersed colloidal crystals based on silica sub-micrometric particles were synthesized using the Stöber-Fink-Bohn process. The control of nucleation and coalescence result in improved characteristics such as high sphericity and very low size dispersion. The resulting silica particles show characteristics suitable for self-assembling across large areas of closely-packed 2D crystal monolayers by an accurate Langmuir-Blodgett deposition process on glass, fused silica and silicon substrates. Due to their special optical properties, colloidal films have potential applications in fields including photonics, electronics, electro-optics, medicine (detectors and sensors), membrane filters and surface devices. The deposited monolayers of silica particles were characterized by means of FESEM, AFM and optical transmittance measurements in order to analyze their specific properties and characteristics. We propose a theoretical calculation for the photonic band gaps in 2D systems using an extrapolation of the photonic behavior of the crystal from 3D to 2D. In this work we show that the methodology used and the conditions in self-assembly processes are decisive for producing high-quality two-dimensional colloidal crystals by the Langmuir-Blodgett technique.

Development, physical-chemical stability and release studies of four alcohol-free spironolactone suspensions for use in pediatrics

Dissolution studies have become of great significance because, in most cases, drug dissolution is the rate-limiting step in the absorption process. As occurs with solid oral dosage forms, heterogeneous disperse systems (suspensions) could also have some problems with their in vitro dissolution. The objective of this study was to evaluate influence of the excipients on the release of spironolactone from four alcohol free suspensions (pharmaceutical compounding) of spironolactone 5 mg/mL suitable for pediatric use. Also the comparison of the physical and chemical stability of the suspensions stored at 4, 25 and 40 ºC over a 60- day period has been studied. Rheological behavior, particle size, a prediction of long-term physical stability, pH and assay of spironolactone by HPLC were assessed at prefixed times. The dissolution profile of each suspension was determined and compared with that of the commercial tablets. A microbiological study of the best formula was also performed. Chemically, the four spironolactone suspensions were stable for 60 days stored at three temperatures; Suspension IV had optimum pH values and the highest recovery percentage. In terms of physical stability, sedimentation occurred in Suspension IV and flotation of spironolactone in Suspensions I, II and III. Suspension III had the highest viscosity and the slowest drug release. Suspension IV was also microbiologically stable for 60 days. In conclusion, Suspension IV had the best properties and the least suitable form was Suspension III, as its high viscosity made it difficult to achieve homogeneous redispersion, and it had the slowest dissolution profile.

Colloidal assembly on magnetically vibrated stripes

We investigate the collective organization of paramagnetic colloidal particles externally driven above the periodic stripes of a uniaxial ferrimagnetic garnet film. An external field modulation induces vibration of the stripe walls and produces random motion of the particles. Defects in the stripe pattern break the symmetry of the potential and favor particle nucleation into large clusters above a critical density. Mismatch between particle size and pattern wavelength generates assemblies with different morphological order. At even higher field strengths, repulsive dipolar interactions between the particles induce cluster melting. We propose a novel approach to generate and externally control a variety of colloidal assemblies.

"In vitro" comparative experimental study of antimicrobial action of mouth washing products

Regular use of mouth rinses modifies the oral habitat, since bacterial populations are submitted to a high selective pressure during the treatment exercised by the active presence of the disinfectant. Mostly mouth rinses are based on the antibacterial effect of Chlorhexidine, Triclosan, essential oils and other antibacterials although other pharmaceutical characteristics can also affect their effectiveness. In this paper we compare"in vitro" the antibacterial effect of different oral rinsing solutions. Minimal Inhibitory Concentrations (MIC) and Minimal Bactericidal Concentrations (MBC) were determined as well as the kinetics of bacterial death in the presence of letal concentrations of the mouth rinses. MIC values expressed as Maximal Inhibitory Dilution (MID) of the mouth rinse ranged from 1 to 1/2048 depending on the microorganism and product, whereas Minimal Biocidal Concentration (MBC), expressed as Maximal Biocidal Dilution (MBD) ranged from 1 to 1/1024, being in general one dilution less than MIC. Maximal Biocidal Dilution is a good tool to measure the actual efficiency of mouth washing solutions. However, kinetics of death seems to be better in our work killing curves demonstrate that bacterial populations are mostly eliminated during the first minute after the contact of bacterial suspension and the mouth-washing solution. In all tested bacterial species mouth-washing solutions tested were able to reduce until suspension treated except 1 and 5

Analysis of vineyard differential management zones and relation to vine development, grape maturity and quality

The objective of research was to analyse the potential of Normalized Difference Vegetation Index (NDVI) maps from satellite images, yield maps and grapevine fertility and load variables to delineate zones with different wine grape properties for selective harvesting. Two vineyard blocks located in NE Spain (Cabernet Sauvignon and Syrah) were analysed. The NDVI was computed from a Quickbird-2 multi-spectral image at veraison (July 2005). Yield data was acquired by means of a yield monitor during September 2005. Other variables, such as the number of buds, number of shoots, number of wine grape clusters and weight of 100 berries were sampled in a 10 rows × 5 vines pattern and used as input variables, in combination with the NDVI, to define the clusters as alternative to yield maps. Two days prior to the harvesting, grape samples were taken. The analysed variables were probable alcoholic degree, pH of the juice, total acidity, total phenolics, colour, anthocyanins and tannins. The input variables, alone or in combination, were clustered (2 and 3 Clusters) by using the ISODATA algorithm, and an analysis of variance and a multiple rang test were performed. The results show that the zones derived from the NDVI maps are more effective to differentiate grape maturity and quality variables than the zones derived from the yield maps. The inclusion of other grapevine fertility and load variables did not improve the results.

The Rose Bengal test in human brucellosis: a neglected test for the diagnosis of a neglected disease

Brucellosis is a highly contagious zoonosis affecting livestock and human beings. The human disease lacks pathognomonic symptoms and laboratory tests are essential for its diagnosis. However, most tests are difficult to implement in the areas and countries were brucellosis is endemic. Here, we compared the simple and cheap Rose Bengal Test (RBT) with serum agglutination, Coombs, competitive ELISA, Brucellacapt, lateral flow immunochromatography for IgM and IgG detection and immunoprecipitation with Brucella proteins. We tested 208 sera from patients with brucellosis proved by bacteriological isolation, 20 contacts with no brucellosis, and 1559 sera of persons with no recent contact or brucellosis symptoms. RBT was highly sensitive in acute and long evolution brucellosis cases and this related to its ability to detect IgM, IgG and IgA, to the absence of prozones, and to the agglutinating activity of blocking IgA at the pH of the test. RBT was also highly specific in the sera of persons with no contact with Brucella. No test in this study outperformed RBT, and none was fully satisfactory in distinguishing contacts from infected patients. When modified to test serum dilutions, a diagnostic titer >4 in RBT resulted in 87.4% sensitivity (infected patients) and 100% specificity (contacts). We discuss the limitations of serological tests in the diagnosis of human brucellosis, particularly in the more chronic forms, and conclude that simplicity and affordability of RBT make it close to the ideal test for small and understaffed hospitals and laboratories.

Late and postmagmatic alterations in the tin-bearing batholith of Ricobayo (Iberian Massif, NW Spain)

The deuteric alteration processes undergone by the granites of the Ricobayo Batholith were: microclinization, chloritization, albitization, muscovitization, tourmalinization and garnetization. These processes must be interpreted in a dynamic context so that the different reactions that take place are the consequence of a successive interaction between rock and fluids. The physicochemical conditions deduced from these fluids are: temperature lower than 600 OC, pressure between 1.5 and 1 Kb, fugacity of oxygen between 10-25 and 10-35 bars, fugacity of sulphur lower than 10-l5 bars, the composition was kept stable and their log (a(K+)/a(Ht)) and log (a(Na+)/a(H+)) varied between 3.8 and 3.2 and between 3.5 and 4.6, respectively, and the pH of the fluids was higher than 5 during the microclinization, muscovitization and tourmalinization, and lower during chloritization and albitization. The deposition of cassiterite occurs with pH episodes that exceed 5.

Estimulació beta-adrenèrgica en la síndrome del destret respiratori agut (SDRA)

Estudi elaborat a partir d’una estada al Royal Brompton Hospital, Londres, Regne Unit, durant octubre i novembre del 2006.Els beneficis de la estimulació beta-adrenèrgica en pacients amb lesió pulmonar aguda (LPA) són coneguts, però no es disposa de dades sobre el possible efecte antiinflamatori. El condensat d'aire exhalat (CAE) és una tècnica no-invasiva de recollida de mostres del tracte respiratori inferior, podent ser útil en la monitorització de patologies respiratòries. S’ha usat marcadors biològics en el CAE de pacients ventilats mecànicament amb LPA per estudiar el possible efecte antiinflamatori que el salbutamol hi podria exercir. El CAE va ser recollit abans i després de l'administració de salbutamol inahalat. Inmediatament després es va mesurar la conductivitat i el pH abans i després de la desgasificació amb heli. Es va mesurar la concentració de nitrits i nitrats. Les mostres varen ser liofilitzades i guardades a -80ºC. La concentració de leucotriè B4 es va mesurar després de la reconstitució de la mostra. Els resultats s'expressen com a mitjana (error estàndard de la mostra). No s'han detectat diferències entre els valors de CAE basals dels pacients amb LPA i els de referència de la població sana de Barcelona. Es conclou doncs que el CAE és una tècnica no invasiva que pot ser usada en la monitorització de paceints ventilats mecànicament. El salbutamol inhalat incrementa de manera significativa el pH del CAE dels paceints amb LPA, tot i que un efecte directe de la inhalació de slabutamol no pot ser desestimat.

Estudis funcionals i de plegament dels dominis d'activació de les procarboxipeptidases

Els dominis d’activació (ADs) de les procarboxipeptidases de la subfamília A/B sempre han sorprès ja que representen una quarta part del proenzim. S’han realitzat alguns estudis per intentar descobrir-ne alguna possible funció alternativa, però no han estat fructífers. El descobriment de l’elevada velocitat de plegament del domini d’activació de la procarboxipeptidasa A2 humana, (ADA2h), emperò, va portar a proposar la possibilitat de que realitzessin una funció d’assistència al plegament del domini enzimàtic. Posteriorment, l’anàlisi del plegament d’ADA2h a pH baix va revelar la capacitat d’aquest domini per formar fibres amiloides, a més de demostrar que un increment de l’estabilitat proteica podia prevenir la formació d’aquests agregats. La profunda caracterització del plegament d’ADA2h va fer que aquesta proteïna fos un bon model amiloidogènic, de manera que es van proposar un seguit d’experiments que s’han desenvolupat en el present treball per tal de conèixer millor aquest procés. S’han dut a terme estudis cinètics d’agregació per tal de valorar la contribució dels diferents aminoàcids de la seqüència polipeptídica, utilitzant 29 variants puntuals d’ADA2h. Es va eliminar la contribució de l’estabilitat mitjançant la utilització d’urea, i per dicroïsme circular conjuntament amb un aparell de flux detingut, es van obtenir dues velocitats diferents, v1 i v2, que corresponen a la formació d’un intermediari i a la seva reorganització, respectivament. Experiments complementaris utilitzant espectroscòpia d’infraroig (IR) revelaren la reorganització de l’estat natiu (en aquest cas) per a donar la forma agregada. Les cinètiques d’IR van mostrar que ADA2h forma l’estructura _ típica de les fibres amiloides, previ desplegament les seves hèlixs-_. Finalment, s’han realitzat estudis de biocomputació per tal d’esbrinar possibles funcions alternatives dels ADs. Les superposicions estructurals semblen mostrar similaritat dels ADs amb dominis de reconeixement d’RNA (RRM). Aquesta hipòtesi s’ha comprovat experimentalment amb ADA4h, mostrant una dèbil, però existent, unió a RNA.

La incidència de l’aprovació de la LO 1/2004, de mesures de protecció integral contra la violència de gènere, a nivell institucional

L’obligació a partir de la LO 1/2004 de realitzar programes formatius en cas de suspensió o substitució d’una pena imposada per un delicte de violència de gènere ha suposat que els operadors jurídics, malgrat el recolzament majoritari a aquesta mesura, es mostrin en desacord amb l’obligatorietat i demanin més discrecionalitat.

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.