Papers by R. Hidalgo-alvarez
Dynamic scaling in surface-controlled colloidal aggregation
Journal of Physics: Condensed Matter, 2000
Aggregation kinetics of latex microspheres in alcohol–water media
Journal of Colloid and Interface Science, 2007
We report zeta potential and aggregation kinetics data on colloidal latex particles immersed in w... more We report zeta potential and aggregation kinetics data on colloidal latex particles immersed in water-alcohol media. Zeta potential values show absolute maxima for volume fractions of alcohol of 0.10 and 0.05 for ethanol and 1-propanol, respectively. For methanol, no maximum of the absolute value of the zeta potential was found. Aggregation kinetics was studied by means of a single-cluster optical sizing equipment and for alcohol volume fractions ranging from 0 to 0.1. The aggregation processes are induced by adding different potassium bromide concentrations to the samples. We expected to find a slowdown of the overall aggregation kinetics for ethanol and 1-propanol, and no significant effect for methanol, as compared with pure water data. That is, we expected the zeta potential to govern the overall aggregation rate. However, we obtained a general enhancement of the aggregation kinetics for methanol and 1-propanol and a general slowdown of the aggregation rate for ethanol. In addition, aggregation data under ethanol show a slower kinetics for large electrolyte concentration than that obtained for intermediate electrolyte concentration. We think that these anomalous behaviors are linked to layering, changes in hydrophobicity of particle surfaces due to alcohol adsorption, complex ion-water-alcohol-surface structuring, and competition between alcohol-surface adsorption and alcohol-alcohol clustering.
The Journal of Physical Chemistry B, 2003
Cuadernos Republicanos, 2021
En este artículo se estudia la evolución experimentada por el Ayuntamiento de Granada desde feb... more En este artículo se estudia la evolución experimentada por el Ayuntamiento de Granada desde febrero de 1922 hasta septiembre de 1932, analizando la estructura socioprofesional de los ediles que formaban parte de la Corporación municipal. Se ha hecho hincapié en el periodo que va desde la dictadura con rey de Primo de Rivera hasta las elecciones del 12 de abril de 1931, que hicieron posible la constitución del Ayuntamiento democrático. Dicha ruptura democrática elevó al gobierno local a parte de la intelligentsia de la ciudad, en la que abundaban profesores universitarios y médicos, desplazando a los propietarios y abogados que durante décadas habían dirigido la administración municipal. Se trató de una transición de la timocracia a la sofocracia, con presencia muy significativa de hombres de ciencia. Se ha realizado un análisis crítico de la labor realizada por los ediles del Ayuntamiento democrático de una ciudad que en 1930 era la décima en pagos al Tesoro por el impuesto de utilidades industriales y la novena por población. Se ha prestado especial atención al catedrático de Química Jesús Yoldi Bereau, que fue alcalde de la ciudad en 1932 y a José Saldaña Pérez, catedrático de Matemáticas del Instituto General y Técnico, primer teniente de alcalde durante el mandato de Yoldi. Por último, se ha mencionado a José Domingo Quílez, catedrático de Física Teórica y Experimental y presidente del Consejo Local de Izquierda Republicana en Granada en 1936.
Stud. hist. Hª cont., 2023
BSTRACT: Within the framework of an ambitious tax reform promoted by the Managing Director of Adm... more BSTRACT: Within the framework of an ambitious tax reform promoted by the Managing Director of Administration, José Calvo Sotelo, and his group of advisers, the personal ID tax was changed in mid-1925. The economic resources thus obtained were intended to finance the Provincial Councils and indirectly to the Town Halls. The Provincial Statute promulgated in March 1925 established the legal framework for this reform. Three rates, applicable to income from work, direct contributions and rentals, were created. Although with limitations, this reform attempted to convert product taxes into income taxes. The rigor of the reform allows us to use this tax as an objective index of the economic power of peripheral elites. As a case study, the application of this tax to the population of Granada has been analyzed. In the ranking of Spanish cities, Granada was fourth in number of ids issued in the first two classes of the three rates.
Keywords: Granada; Provincial Statute; Personal id tax; Peripheral elite.
Polymers for Advanced Technologies, 1996
Monodisperse core-shell stable latexes with reactive methylchloride surface functionalities were ... more Monodisperse core-shell stable latexes with reactive methylchloride surface functionalities were prepared at two different reaction temperatures. The reaction temperature played an important role in the amount of reactive functional groups. The covalent coupling had an efficiency of more than 50%. Antibodies covalently bound to functionalized polystyrene beads were used to detect corresponding antigens by nephelomet y.
Strategies to Improve the Colloidal Stability and the Reactivity of Immunolatex Beads
Journal of Dispersion Science and Technology, 1996
The aim of the present work is to study the influence of the sequential or competitive adsorption... more The aim of the present work is to study the influence of the sequential or competitive adsorption of anti-HSA (Human Serum Albumin) IgG and RSA (Rabbit Serum Albumin) onto a negatively charged polystyrene latex on the colloidal stability of the immunoiatex (IgG-RSA/latex). Anionic (1-2) latex was prepared by surfactant free emulsion polymerization. Adsorption of IgG and RSA on the latex
Tribology International, 2021
A new formulation is proposed to lubricate tribopairs in extreme conditions where the amount of l... more A new formulation is proposed to lubricate tribopairs in extreme conditions where the amount of lubricant is small and the lubricating region highly confined. It is composed of non-magnetic solid lubricants dispersed in an oil-based ferrofluid. When this inverse ferrofluid (IFF) is magnetically activated, the lubricant particles are subjected to magnetophoretic forces. By using appropriate magnetic field gradients, they can be driven to the region of interest and thus control the friction locally. The rheological and tribological performances of three IFF formulations are evaluated in several conditions of applied magnetic field strength and shear flow rates.
Time-resolved measurements of the cluster-size distributions arising in charge-heteroaggregation processes
... Since this value is smaller than the Bjerrum length, the electrical double layer may be consi... more ... Since this value is smaller than the Bjerrum length, the electrical double layer may be considered to be completely suppressed. ... 1. Bandini P, Prestidge CA, Ralston J (2001) Miner Eng 14:487 2. Luna-Xavier JL, Guyot A, Bourgeat-Lami E (2002) J Colloid Interface Sci 250:82 3 ...
The hydrophobic effect as a driving force for charge inversion in colloids
Soft Matter, 2009
... Alberto Martín-Molinaa, Carles Calerob, Jordi Faraudo*b, Manuel Quesada-Pérezc, Alex Travesse... more ... Alberto Martín-Molinaa, Carles Calerob, Jordi Faraudo*b, Manuel Quesada-Pérezc, Alex Travessetd and Roque Hidalgo-Álvareza. a Grupo de ... Cations such as those based on phenyl groups (Ph 4 As + , Ph 4 Sb + ,
) have Gibbs energies of transfer from water to hydrophobic ...
Despite of their importance for many industrial applications and the understanding of natural phe... more Despite of their importance for many industrial applications and the understanding of natural phenomena, heteroaggregation processes have not been in the focus of attention of the scientific community until quite recently. Still nowadays, their tremendously complex nature turns a detailed experimental and theoretical treatment of these processes into a difficult task. Hence, we have limited the scope of this review to electrostatic heteroaggregation arising in symmetric two-component systems, i.e., those with the same concentration of cationic and anionic particles. The short and long-time aggregation kinetics will be addressed not only from an experimental but also from a theoretical and simulation point of view at almost six orders of magnitude of electrolyte concentration. The different aggregation regimes will be identified and described in detail.
Jesús Yoldi Bereau, el químico olvidado
Un Siglo De Estudios De Quimica En Granada 2014 Isbn 978 84 338 5651 7 Pags 147 161, 2014
Tribology Letters, 2010
Biocompatible microgels have been demonstrated to act as excellent lubricants, however, the influ... more Biocompatible microgels have been demonstrated to act as excellent lubricants, however, the influence of the continuum on their overall mechanical performance has been neglected so far. In this work, the mechanical performance of colloidal whey protein microgels (hydrodynamic diameter B100 nm measured using dynamic light scattering and atomic force microscopy) of different rigidity dispersed in Newtonian (buffer and corn syrup) or complex non-Newtonian fluids (xanthan gum) is investigated for the first time via rheology and soft tribology. Dispersions of both soft microgels (G 0 B 100.0 Pa) and hard microgels (G 0 B 10.0 kPa) were observed to act as thickeners in buffer as well as in low viscosity corn syrup and correspondingly reduced the friction, latter decreased as a function of the increased rigidity of the microgels. Differently, in high viscosity continuum, the microgels acted as thinning agents and increased the friction. In the lubrication limit, microgels in buffer or corn syrup behaved as Newtonian fluids with effective viscosity corresponding to their second Newtonian plateau value (Z N). However, the lubrication performance of the microgels dispersed in the complex fluid (xanthan gum) could not be described quantitatively by Z N. For the low viscosity xanthan gum, the microgels had no influence on friction. Nevertheless, for the high viscosity counterparts, the soft microgels acted as thinning agents whilst the hard microgels accelerated the onset of elastohydrodynamic regime. This study demonstrates that microgels act as viscosity modifiers directly influencing the tribological performance, depending upon a subtle interplay of rheological properties of the particles and continuum.
Electrokinetic study of cationic polystyrene latex covered by carbopol polyelectrolyte
Colloidal dispersions, suspensions, and aggregates-Formation and structure of stable aggregates in binary diffusion-limited cluster-cluster aggregation processes
Physical Review E, 2000
Though the notion of effective charge has been widely used to fit experimental data, the possibil... more Though the notion of effective charge has been widely used to fit experimental data, the possibility of predicting this adjustable parameter through a model remains unclear. A likely reason for this is the complexity involved in the theoretical approaches in the case of fluids with large asymmetries between their components. This paper deals with several condensation theories for spherical colloids, developed to provide effective charge values from simple models. Liquidlike structures are formed in colloidal dispersions for a set of latexes with different properties ͑charge, size, and polymeric composition͒. Effective charges are determined from experimental structure factors using a Derjaguin-Landau-Verwey-Overbeek potential and an Ornstein-Zernike scheme. The numerical coincidence between effective and post-condensation charges is fairly acceptable only for latexes with small size and charge. A simple approach based on the Manning condensation theory for linear polyelectrolytes is also discussed.
Physical Review E, 1997
In this paper the stability domains of immunoglobulin ͑IgG fragment͒ F͑abЈ) 2 -polymer systems ha... more In this paper the stability domains of immunoglobulin ͑IgG fragment͒ F͑abЈ) 2 -polymer systems have been examined using a low-angle scattering technique. The rates of aggregate formation are expressed in terms of a stability ratio as a function of electrolyte concentration. After the usual rapid aggregation achieved at a certain ionic strength ͑critical coagulation concentration͒, an abnormal stabilization is observed with increasing ionic strength. This exceptional stability at high electrolyte concentration cannot be explained by the Derjaguin,
Physical Review E, 2003
A theoretical model for describing the initial stages of the aggregation of partially covered col... more 
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Papers by R. Hidalgo-alvarez
Keywords: Granada; Provincial Statute; Personal id tax; Peripheral elite.