Interfacial tension measurements using a new axisymmetric drop/bubble shape technique.

This paper introduces a new mathematical model that is used to compute either the interfacial tension of quiescent axisymmetric pendant/sessile drops and pendant/captive bubbles. This model consists of the Young-Laplace equation, that describes interface shape, together with suitable boundary conditions that guarantee a prescribed volume of drops/bubbles and a fixed position in the capillary. In order to solve the problem numerically, the Young-Laplace equation is discretized by using numerical differentiation and the numerical solutions are obtained applying the well-know Newton method. The paper contains a validation of the new methodology presented for what theoretical bubble/drops are used. Finally, some numerical results are presented for both drops and bubbles of water as well as several surfactant solutions to demonstrate the applicability, versatility and reproducibility of the proposed methodology.

Effect of Hydrofluoric Acid Etching Time on Titanium Topography, Chemistry, Wettability, and Cell Adhesion.

Titanium implant surface etching has proven an effective method to enhance cell attachment. Despite the frequent use of hydrofluoric (HF) acid, many questions remain unresolved, including the optimal etching time and its effect on surface and biological properties. The objective of this study was to investigate the effect of HF acid etching time on Ti topography, surface chemistry, wettability, and cell adhesion. These data are useful to design improved acid treatment and obtain an improved cell response. The surface topography, chemistry, dynamic wetting, and cell adhesiveness of polished Ti surfaces were evaluated after treatment with HF acid solution for 0, 2; 3, 5, 7, or 10 min, revealing a time-dependent effect of HF acid on their topography, chemistry, and wetting. Roughness and wetting increased with longer etching time except at 10 min, when roughness increased but wetness decreased. Skewness became negative after etching and kurtosis tended to 3 with longer etching time. Highest cell adhesion was achieved after 5-7 min of etching time. Wetting and cell adhesion were reduced on the highly rough surfaces obtained after 10-min etching time.

Topographic characterisation of dental implants for commercial use.

BACKGROUND: To characterize the surface topography of several dental implants for commercial use. MATERIAL AND METHODS: Dental implants analyzed were Certain (Biomet 3i), Tissue Level (Straumann), Interna (BTI), MG-InHex (MozoGrau), SPI (Alphabio) and Hikelt (Bioner). Surface topography was ascertained using a confocal microscope with white light. Roughness parameters obtained were: Ra, Rq, Rv, Rp, Rt, Rsk and Rku. The results were analysed using single-factor ANOVA and Student-Neuman-Keuls (p<0.05) tests. RESULTS: Certain and Hikelt obtained the highest Ra and Rq scores, followed by Tissue Level. Interna and SPI obtained lower scores, and MG-InHex obtained the lowest score. Rv scores followed the same trend. Certain obtained the highest Rp score, followed by SPI and Hikelt, then Interna and Tissue Level. MG-InHex obtained the lowest scores. Certain obtained the highest Rt score, followed by Interna and Hikelt, then SPI and Tissue Level. The lowest scores were for MG-InHex. Rsk was negative (punctured surface) in the MG-InHex, SPI and Tissue Level systems, and positive (pointed surface) in the other systems. Rku was higher than 3 (Leptokurtic) in Tissue Level, Interna, MG-InHex and SPI, and lower than 3 (Platykurtic) in Certain and Hikelt. CONCLUSIONS: The type of implant determines surface topography, and there are differences in the roughness parameters of the various makes of implants for clinical use.

Clinical Practice Guidelines for Diagnosis and Management of Hypersensitivity Reactions to Contrast Media.

The objective of these guidelines is to ensure efficient and effective clinical practice. The panel of experts who produced this consensus document developed a research protocol based on a review of the literature. The prevalence of allergic reactions to iodinated contrast media (ICM) is estimated to be 1:170 000, that is, 0.05%-0.1% of patients undergoing radiologic studies with ICM (more than 75 million examinations per year worldwide). Hypersensitivity reactions can appear within the first hour after administration (immediate reactions) or from more than 1 hour to several days after administration (nonimmediate or delayed reactions). The risk factors for immediate reactions include poorly controlled bronchial asthma, concomitant medication (eg, angiotensin-converting enzyme inhibitors, ß-blockers, and proton-pump inhibitors), rapid administration of the ICM, mastocytosis, autoimmune diseases, and viral infections. The most common symptoms of immediate reactions are erythema and urticaria with or without angioedema, which appear in more than 70% of patients. Maculopapular rash is the most common skin feature of nonimmediate reactions (30%-90%). Skin and in vitro tests should be performed for diagnosis of both immediate and nonimmediate reactions. The ICM to be administered will therefore be chosen depending on the results of these tests, the ICM that induced the reaction (when known), the severity of the reaction, the availability of alternative ICM, and the information available on potential ICM cross-reactivity. Another type of contrast media, gadolinium derivatives, is used used for magnetic resonance imaging. Although rare, IgE-mediated reactions to gadolinium derivatives have been reported.

Effect of root planing on surface topography: an in-vivo randomized experimental trial.

BACKGROUND AND OBJECTIVE: The root surface topography exerts a major influence on clinical attachment and bacterial recolonization after root planing. In-vitro topographic studies have yielded variable results, and clinical studies are necessary to compare root surface topography after planing with current ultrasonic devices and with traditional manual instrumentation. The aim of this study was to compare the topography of untreated single-rooted teeth planed in vivo with a curette, a piezoelectric ultrasonic (PU) scraper or a vertically oscillating ultrasonic (VOU) scraper. MATERIAL AND METHODS: In a randomized experimental trial of 19 patients, 44 single-rooted teeth were randomly assigned to one of four groups for: no treatment; manual root planing with a curette; root planing with a PU scraper; or root planing with a VOU scraper. Post-treatment, the teeth were extracted and their topography was analyzed in 124 observations with white-light confocal microscopy, measuring the roughness parameters arithmetic average height, root-mean-square roughness, maximum height of peaks, maximum depth of valleys, absolute height, skewness and kurtosis. RESULTS: The roughness values arithmetic average height and root-mean-square roughness were similar after each treatment and lower than after no treatment ( p < 0.05). Absolute height was lower in the VOU group than in the untreated ( p = 0.0026) and PU (p = 0.045) groups. Surface morphology was similar after the three treatments and was less irregular than in the untreated group. Values for the remaining roughness parameters were similar among all treatment groups ( p > 0.05). CONCLUSION: Both ultrasonic devices reduce the roughness, producing a similar topography to that observed after manual instrumentation with a curette, to which they appear to represent a valid alternative.

Bile salts at the air-water interface: adsorption and desorption.

Bile salts (BS) are bio-surfactants which constitute a vital component in the process of fat digestion. Despite the importance of the interfacial properties in their biological role, these have been scarcely studied in the literature. In this work, we present the adsorption-desorption profiles of two BS (NaTC and NaGDC) including dilatational rheology. Findings from this study reveal very different surface properties of NaTC and NaGDC which originate from different complexation properties relevant to the digestion process. Dynamic adsorption curves show higher adsorption rates for NaTC and suggest the existence of various conformational regimes in contrast to NaGDC which presents only one conformational regime. This is corroborated by analysis of the adsorption isotherms and more in detail by the rheological behaviour. Accordingly, the dilatational response at 1Hz displays two maxima of the dilatational modulus for NaTC as a function of bulk concentration, in contrast to NaGDC which displays only one maximum. The desorption profiles reveal that NaTC adopts an irreversibly adsorbed form at high surface coverage whereas NaGDC fully desorbs from the surface within the whole range of concentrations used. Analysis of the adsorption-desorption profiles provides new insight into the surface properties of BS, suggesting a surface complexation of NaTC. This knowledge can be useful since through interfacial engineering we might control the extent of lipolysis providing the basis for the rational design of food products with tailored digestibility.

Equilibrium contact angle or the most-stable contact angle?

It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation.

Simplificación a monoterapia con lopinavir/ritonavir en niños infectados por el virus de la inmunodeficiencia humana / Simplification to lopinavir/ritonavir monotherapy in HIV-infected children

La monoterapia con lopinavir/ritonavir como estrategia de simplificación tiene el potencial de minimizar la toxicidad del tratamiento antirretroviral sin perder eficacia en casos seleccionados según estudios realizados en adultos; sin embargo, existen pocos datos en niños. Describimos una serie de 5 casos pediátricos tratados con este régimen durante una mediana de 112 semanas. Un niño con problemas de adhesión requirió intensificación de tratamiento por fallo virológico, presentando nuevamente carga viral indetectable. Ensayos clínicos aleatorizados controlados son necesarios para evaluar la eficacia de esta estrategia en niños y establecerlas recomendaciones apropiadas (AU)

Lopinavir/ritonavir monotherapy as a simplification strategy has the potential to minimize antiretroviral treatment toxicity without losing efficacy in selected cases, according to studies in adults, but little is known in paediatric patients. We report 5 children on this regimen for a median time of 112 weeks. One child with suboptimal adherence required intensification therapy to re-suppress viral load. Randomised controlled trials are needed to evaluate the efficacy of this strategy in children in order to make appropriate recommendations (AU)

Comparison of the relaxation of sessile drops driven by harmonic and stochastic mechanical excitations.

Currently, there is no conclusive evidence regarding the global equilibrium condition of vibrated drops. However, it is well-known that vibration of sessile drops effectively reduces the contact angle hysteresis. In this work, applying a recent methodology for evaluating the most-stable contact angle, we examined the impact of the type of excitation signal (random signal versus periodical signal) on the values of the most-stable contact angle for polymer surfaces. Using harmonic signals, the oscillation frequency affected the postvibration contact angle. Instead, the white noise signal enabled sessile drops to relax regardless of their initial configuration. In spite of that, the values of most-stable contact angle obtained with different signals mostly agreed. We concluded that not only the amount of relaxation can be important for relaxing a sessile drop but also the rate of relaxation. Together with receding contact angle, most-stable contact angle, measured with the proposed methodology, was able to capture the thermodynamic changes of "wetted" polymer surfaces.

Comparison of sessile drop and captive bubble methods on rough homogeneous surfaces: a numerical study.

Quasi-static experiments using sessile drops and captive bubbles are the most employed methods for measuring advancing and receding contact angles on real surfaces. These observable contact angles are the most easily accessible and reproducible. However, some properties of practical surfaces induce certain phenomena that cause a built-in uncertainty in the estimation of advancing and receding contact angles. These phenomena are well known in surface thermodynamics as stick-slip phenomena. Following the work of Marmur (Marmur, A. Colloids Surf., A 1998, 136, 209-215), where the stick-slip effects were studied with regard to sessile drops and captive bubbles on heterogeneous surfaces, we developed a novel extension of this study by adding the effects of roughness to both methods for contact angle measurement. We found that the symmetry between the surface roughness problem and the chemical heterogeneity problem breaks down for drops and bubbles subjected to stick-slip effects.

[Simplification to lopinavir/ritonavir monotherapy in HIV-infected children]. / Simplificación a monoterapia con lopinavir/ritonavir en niños infectados por el virus de la inmunodeficiencia humana.

Lopinavir/ritonavir monotherapy as a simplification strategy has the potential to minimize antiretroviral treatment toxicity without losing efficacy in selected cases, according to studies in adults, but little is known in paediatric patients. We report 5 children on this regimen for a median time of 112 weeks. One child with suboptimal adherence required intensification therapy to re-suppress viral load. Randomised controlled trials are needed to evaluate the efficacy of this strategy in children in order to make appropriate recommendations.

Wetting on axially-patterned heterogeneous surfaces.

Contact angle variability, leading to errors in interpretation, arises from various sources. Contact angle hysteresis (history-dependent wetting) and contact angle multiplicity (corrugation of three-phase contact line) are irrespectively the most frequent causes of this uncertainty. Secondary effects also derived from the distribution of chemical defects on solid surfaces, and so due to the existence of boundaries, are the known "stick/jump-slip" phenomena. Currently, the underlying mechanisms in contact angle hysteresis and their connection to "stick/jump-slip" effects and the prediction of thermodynamic contact angle are not fully understood. In this study, axial models of smooth heterogeneous surface were chosen in order to mitigate contact angle multiplicity. For each axial pattern, advancing, receding and equilibrium contact angles were predicted from the local minima location of the system free energy. A heuristic model, based on the local Young equation for spherical drops on patch-wise axial patterns, was fruitfully tested from the results of free-energy minimization. Despite the very simplistic surface model chosen in this study, it allowed clarifying concepts usually misleading in wetting phenomena.

Imaging techniques applied to characterize bitumen and bituminous emulsions.

The purpose of this article is to present some important advances in the imaging techniques currently used in the characterization of bitumen and bituminous emulsions. Bitumen exhibits some properties, such as a black colour and a reflecting surface at rest, which permit the use of optical techniques to study the macroscopic behaviour of asphalt mixes in the cold mix technology based on emulsion use. Imaging techniques allow monitoring in situ the bitumen thermal sensitivity as well as the complex phenomenon of emulsion breaking. Evaporation-driven breaking was evaluated from the shape of evaporating emulsion drops deposited onto non-porous and hydrophobic substrates. To describe the breaking kinetics, top-view images of a drying emulsion drop placed on an aggregate sheet were acquired and processed properly. We can conclude that computer-aided image analysis in road pavement engineering can elucidate the mechanism of breaking and curing of bituminous emulsion.

Resultados perinatales de las gestantes inmigrantes / Perinatal outcomes in immigrant women

Objetivos Conocer las características de los recién nacidos de las gestantes inmigrantes atendidas en nuestro medio y compararlas con las de los recién nacidos de madre autóctona. Pacientes y métodos Se incluyen los recién nacidos atendidos en la Sección de Neonatología del Hospital del Mar de Barcelona en los años 2003 y 2004 (n 5 2.735). Los datos eran recogidos de forma prospectiva en una base de datos. Las gestantes inmigrantes se clasificaron en 6 regiones (Europa del Este, resto de Europa, África, Asia, América Latina y otras). Se establecieron 12 diagnósticos que se compararon entre recién nacidos autóctonos e inmigrantes, y se calculó el riesgo relativo de éstos. Resultados Hubo 1.296 recién nacidos autóctonos (47,8 %) y 1.416 inmigrantes (52,2 %). Las gestantes inmigrantes presentaban mayor incidencia de estado portador de antígeno de superficie de la hepatitis B (HBsAg) (2,0 % frente al 1,0 %) y menor de anticuerpos contra el virus de la hepatitis C (AcVHC) (0,8 % frente al 2,0 %; p < 0,01). Sólo hubo una gestante inmigrante positiva al virus de la inmunodeficiencia humana (VIH), frente a 14 españolas (p < 0,01), y el consumo de drogas era menor en las inmigrantes (0,4 % frente al 4,0 %; p < 0,01). Los recién nacidos inmigrantes tenían menos incidencia de prematuridad (6,0 % frente al 7,6 %) y de bajo peso (2,3 % frente al 4,6 %; p < 0,01). No hubo diferencias significativas de distrés respiratorio ni de acidosis fetal. La incidencia de riesgo de infección neonatal era mayor en los recién nacidos inmigrantes (49,9 % frente al 40,6 %; p < 0,01). Conclusiones Los recién nacidos de madre inmigrante presentan en nuestro medio mejores resultados perinatales que los autóctonos, siendo las complicaciones más frecuentes secundarias a un control prenatal inadecuado

Objectives To describe the characteristics of immigrant women's newborns in our environment, and to compare them with those of native women's newborns. Patients and methods All newborns attended in the Neonatology Section of Hospital del Mar in Barcelona, Spain, in 2003 and 2004 were included (n 5 2,735). Data were prospectively collected in a database. Pregnant immigrant women were classified in 6 regions (Eastern Europe, the rest of Europe, Africa, Asia, Latin America and other countries). Twelve diagnoses were defined and compared between native newborns and those of immigrant parents, and their relative risks were calculated. Results There were 1,296 native newborns (47.8 %) and 1,416 of immigrant origin (52.2 %). Immigrant women showed a higher rate of HBsAg carrier status (2.0 % versus 1.0 %) and a lower rate of hepatitis C virus infection (0.8 % vs 2.0 %; p < 0.01). There was only one HIV-positive pregnant immigrant woman compared with 14 Spanish women (p < 0.01), and drug use was lower in the immigrant group (0.4 % vs 4.0 %; p < 0.01). Immigrant newborns had a lower rate of prematurity (6.0 % vs 7.6 %) and of low birthweight (2.3 % vs 4.6 %; p < 0.01). There were no significant differences in the rate of respiratory distress or fetal acidosis. The incidence of neonatal infection risk was higher in immigrant newborns (49.9 % vs 40.6 %; p < 0.01). Conclusions In our environment, immigrant mothers' newborns have better perinatal outcomes than native newborns. The most frequent complications are secondary to an inadequate