Reline aqueous solutions behaving as liquid mixtures of H-bonded co-solvents: microphase segregation and formation of co-continuous structures as indicated by Brillouin and 1H NMR spectroscopies.

Deep eutectic solvents (DESs) offer a suitable alternative to conventional solvents in terms of both performance and cost-effectiveness. Some DESs also offer certain green features, the greenness of which is notoriously enhanced when combined with water. Aqueous DES dilutions are therefore attracting great attention as a novel green medium for biotechnological processes, with the aqueous dilutions of reline - a DES composed of urea and choline chloride - being one of the most studied systems. Despite their macroscopic homogeneous appearance, both 1H NMR spectroscopic studies and molecular dynamics simulations have revealed the occurrence of certain dynamic heterogeneity at a microscopic molecular level. Ultrasonic measurements were also used with the aim of getting further insights but nonconclusive results were obtained. Herein, we have studied aqueous reline dilutions by Brillouin spectroscopy given its proved suitability for detecting local structure rearrangements in liquid mixtures of H-bonded co-solvents. Brillouin spectroscopy revealed the formation of a co-continuous structure resulting from local structure rearrangements and micro-segregation into aqueous and DES phases. Interestingly, there is agreement between 1H NMR and Brillouin spectroscopy when pointing to the DES content where microphase segregation and formation of co-continuous structures occurred.

Wettability influence on the onset temperature of pool boiling: Experimental evidence onto ultra-smooth surfaces.

In this article we study systematically the effect of wettability on the onset of boiling on the same nanometrically smooth surface. By grafting different monolayers of molecules, we were able to explore the wettability from the equilibrium static contact angle, θ0=0° to θ0=110°, without changing the surface topography. The superheat temperature at the onset of pool boiling was measured and eventually a non-classical trend of TONB as a function of wettability was observed. The nucleation site densities for the different grafting cases were also measured by image analysis. Moreover, we propose a novel theoretical interpretation to this phenomenon linking nucleation and the molecular diffusion coefficient. MD simulation results support this approach.

Superhydrophobicity and liquid repellency of solutions on polypropylene.

The sliding of drops of aqueous solutions of organic liquids over a superhydrophobic polypropylene (SH-PP) surface has been studied experimentally. The multi-scale roughness of this surface is intrinsically inhomogeneous. Careful analysis of the wettability of each solution enables us to establish the statistics of the advancing and receding contact angles. We consider a threshold value of the receding static contact angle, above which drop sliding and rebound are facilitated as the criterion for superhydrophobicity. The percentage of receding contact angles greater than this threshold is then used as a practical index of superhydrophobicity (SHI). The variation of the SHI is compared with surface tension of the solution and various wetting parameters. A linear correlation is found between the SHI and the work of wetting defined by γ(LG)cosθ(0) where γ(LG) is the surface tension of the solution and θ(0) is the static contact angle of the solution over the corresponding smooth surface. Such a correlation can be used as a predictive tool of the superhydrophobicity of a given surface with various liquids.

Influence of the wettability on the boiling onset.

Experimental investigation of pool boiling is conducted in stationary conditions over very smooth bronze surfaces covered by a very thin layer of gold presenting various surface treatments to isolate the role of wettability. We show that even with surfaces presenting mean roughness amplitudes below 10 nm the role of surface topography is of importance. The study shows also that wettability alone can trigger the boiling and that the boiling position on the surface can be controlled by chemical grafting using for instance alkanethiol. Moreover, boiling curves, that is, heat flux versus the surface superheat (which is the difference between the solid surface temperature and the liquid saturation temperature), are recorded and enabled to quantify, for this case, the significant reduction of the superheat at the onset of incipient boiling due to wettability.

Experimental evidence of the role of viscosity in the molecular kinetic theory of dynamic wetting.

We report an experimental study of the dynamics of spontaneous spreading of aqueous glycerol drops on glass. For a range of glycerol concentrations, we follow the evolution of the radius and contact angle over several decades of time and investigate the influence of solution viscosity. The application of the molecular kinetic theory to the resulting data allows us to extract the coefficient of contact-line friction ζ, the molecular jump frequency κ(0), and the jump length λ for each solution. Our results show that the modified theory, which explicitly accounts for the effect of viscosity, can successfully be applied to droplet spreading. The viscosity affects the jump frequency but not the jump length. In combining these data, we confirm that the contact-line friction of the solution/air interface against the glass is proportional to the viscosity and exponentially dependent on the work of adhesion.

Can we predict the spreading of a two-liquid system from the spreading of the corresponding liquid-air systems?

We present new data obtained from the spreading of a series of oil droplets, on top of a hydrophobic grafted silicon substrate, in air and immersed in water. We follow the contact angle and radius dynamics of hexane, dodecane, hexadecane, dibutyl phthalate, and squalane from the first milliseconds to approximately 1 s. Analysis of the images allows us to make several hundred contact angle and droplet radius measurements with great accuracy. The G-Dyna (Seveno et al. Langmuir 2010, 25, 13034) software is then used to fit the data with one of the wetting theories, the molecular-kinetic theory (MKT) (Blake et al. J. Colloid Interface Sci.1969, 30, 421), which takes into account the dissipation at the three-phase zone at the contact line. This theory allows us to extract the coefficient of friction of the contact line, which expresses the relationship between the driving force, that is, the unbalanced Young force, and the contact-line velocity V. It is first shown that the MKT is appropriate to describe the experimental data and then that the contact-line friction is a linear function of the viscosity as theoretically predicted. This is checked for oil-air and oil-water systems. A linear relation between the contact-line friction measured in oil-water systems and the contact-line frictions of the parent single liquid system seems plausible. To the best of our knowledge, this is the first trial to establish a link between the dynamics of wetting in liquid-liquid and in liquid-air systems.

Structural and thermodynamic studies of n-butanol.

We have conducted x-ray diffraction, calorimetric and Brillouin-scattering experiments on n-butanol between 77 and 300 K, aiming to explore the physical nature of the so-called 'glacial state' previously found in n-butanol as well as in triphenyl phosphite. In addition to our structural and thermodynamic studies of the liquid-glass transition and of the stable crystal state in n-butanol, we have found that the metastable 'glacial state' that can be obtained in the temperature range 125-160 K is not a second amorphous state, but rather the result of a frustrated or aborted crystallization process that produces plenty of nanocrystallites embedded in a disordered matrix. The crystalline order of these nanocrystallites of the 'glacial phase' is exactly the same as that well observed in the fully ordered stable crystal into which it transforms by heating above 160 K.

Dynamics of wetting revisited.

We present new spreading-drop data obtained over four orders of time and apply our new analysis tool G-Dyna to demonstrate the specific range over which the various models of dynamic wetting would seem to apply for our experimental system. We follow the contact angle and radius dynamics of four liquids on the smooth silica surface of silicon wafers or PET from the first milliseconds to several seconds. Analysis of the images allows us to make several hundred contact angle and droplet radius measurements with great accuracy. The G-Dyna software is then used to fit the data to the relevant theory (hydrodynamic, molecular-kinetic theory, Petrov and De Ruijter combined models, and Shikhmurzaev's formula). The distributions, correlations, and average values of the free parameters are analyzed and it is shown that for the systems studied even with very good data and a robust fitting procedure, it may be difficult to make reliable claims as to the model which best describes results for a given system. This conclusions also suggests that claims based on smaller data sets and less stringent fitting procedures should be treated with caution.

Concentration and temperature dependence of the refractive index of ethanol-water mixtures: influence of intermolecular interactions.

The temperature and concentration dependence of the refractive index, nD(x, T), in ethanol-water mixtures agrees with previous data in the ethanol-rich concentration range. The refractive index versus concentration x determined at 20 degrees C shows the expected maximum at about 41 mol% water (22 mass% water). The temperature derivative of the refractive index, dnD/dT, shows anomalies at lower water concentrations at about 10 mol% water but no anomaly at 41 mol% water. Both anomalies are related to intermolecular interactions, the one in nD seems to be due to molecular segregation and cluster formation while the origin of the second one in dnD/dT is still not clear.

An innovative method to control the incipient flow boiling through grafted surfaces with chemical patterns.

The onset of flow boiling of a liquid is linked to the superheat condition that is necessary to activate the nucleation sites on contacting surfaces. The nucleation sites are usually represented by cavities in the rough surface of the heat exchanger. On smooth surfaces, the region where bubble detachment does not occur due to the lack of superheating may constitute a serious limitation for microfluidic devices. This paper shows the first experimental evidence that the position of the active nucleation sites can be controlled through chemical patterning of smooth surfaces: in this study, the heated surfaces are chemically grafted with alkylsilane self-assembled monolayers by microcontact printing. The analysis of the propagation of the bubble zone area quantitatively shows that the bubbles remain localized on top of the grafted zone and that, in the initial phase of the experiment, the center of mass of the bubble zone only moves along the vertical axis, without lateral drift.

Superhydrophobic surfaces from various polypropylenes.

Superhydrophobic surfaces were prepared from solutions of isotactic polypropylenes of various molecular weights using soft chemistry. Varying the conditions of the experiments (polymer concentration and initial amount of the coated solution) allowed us to optimize the superhydrophobic behavior of the polymer film. Results show that decreasing the concentration and/or film thicknesses decreases the probability to get superhydrophobicity for all polypropylenes tested. Measurement and analysis of advancing and receding contact angles as well as estimation of surface homogeneity were performed. Similar results were obtained with syndio- as well as atactic polypropylenes.

Drop impact on porous superhydrophobic polymer surfaces.

Water drop impacts are performed on porous-like superhydrophobic surfaces. We investigate the influence of the drop size and of the impact velocity on the event. The Cassie-Baxter/Wenzel transition is observed to be a function of the drop size, as well as the outcomes of the impact or deposition process, which can be deposition, rebound, sticking, or fragmentation. A quantitative analysis on the experimental conditions required to observe rebound is provided. Our analysis shows that the wettability hysteresis controls the limit between deposition and rebound events. This limit corresponds to a constant Weber number. A survey of literature results on impact over patterned superhydrophobic surfaces is provided as a comparison.

Contact-line friction of liquid drops on self-assembled monolayers: chain-length effects.

The static and dynamic wetting properties of self-assembled alkanethiol monolayers of increasing chain length were studied. The molecular-kinetic theory of wetting was used to interpret the dynamic contact angle data and evaluate the contact-line friction on the microscopic scale. Although the surfaces had a similar static wettability, the coefficient of contact-line friction zeta0 increased linearly with alkyl chain length. This result supports the hypothesis of energy dissipation due to a local deformation of the nanometer-thick layer at the contact line.

Low inertia impact dynamics for nanodrops.

Simulations of a droplet impacting a flat solid surface with a small initial speed have been studied using molecular dynamics. Approximating the shape of the drop by a spheroid, spreading radii, and dynamic contact angles are measured. The data reproduce well experimental results from literature. We show that the difference between the equilibrium and the dynamic contact angle cosines, that is, the spontaneous driving force, versus the spreading velocity of the three-phase line varies with impact speed and consists of two distinct regimes which can be described by existing models of moving contact lines.

Evaluación de la salud oral en una población de drogodependientes / Evaluation of the oral heath in a drogodependientes population

Introducción: El objetivo del presente trabajo es analizar la situación de salud oral en una población adulta drogodependiente para instaurar un programa de educación sanitaria. Pacientes y métodos: Estudio descriptivo transversal. Se han evaluado un total de 53 sujetos comprendidos entre los 24 y 44 años de edad pertenecientes a un centro de ayuda al drogodependiente de la Comunidad de Madrid. La exploración se realizó de forma estandarizada en el propio centro, siguiendo los criterios de diagnostico y la ficha de soporte de la OMS. El análisis estadístico fue analizado mediante el sistema SPSS, registrando frecuencias, medias y desviación típica. Resultados: Los resultados obtenidos muestran un consumo de heroína en un 83 por ciento (n=44) de los sujetos, siendo portadores de VIH un 45,3 por ciento (n=24). La media del CAOD fue de 13.6 (+/-6.02) no encontrándose diferencias estadísticamente significativas entre los sujetos con VIH (CAOD=14.4+/-5.2) y sujetos sin VIIH (CAOD=13.03+/-6.62). El estado de la mucosa oral revela la candidiasis oral como la patología mas prevalente con un 13.2 por ciento (n=7) de los sujetos, siendo los chasquidos la patología de ATM más registrada (64.2 por ciento, n=34). Conclusiones: La alta prevalencia de caries en estos sujetos demuestran que son población de alto riesgo de caries siendo necesaria una estrecha colaboración entre los sectores sociales y sanitarios (AU)

Estudio epidemiológico en adultos discapacitados psíquicos: Parte III. Maloclusión y otras anomalías dentarias / Epidemiological variables of oral healh in handicapped adults. Part III. Maloclussion and teeth abnormalities

El objetivo del presente trabajo es analizar la prevalencia de maloclusiones y otras alteraciones dentarias en una población adulta no institucionalizada con minusvalías psíquicas. El total de sujetos explorados fue de 121 adultos comprendidos entre los 20 y 40 años de edad, con un grado de retraso mental leve-moderado. Por patología médica un 58 por ciento, fueron diagnosticados de parálisis cerebral y un 42 por ciento con síndrome de Down. La exploración clínica reveló que un total de 33 por ciento de individuos tenían una clase III molar de Angle, alcanzando en el síndrome de Down una frecuencia de 68,7 por ciento. También las mordidas abiertas fue la relación anterior más predominante en el total de la muestra. En relación a las anomalías dentarias destacamos en pacientes con síndrome de Down la abrasión dentaría con un 27 por ciento, microdoncia con un 25 por ciento y agenesias dentarias con un 19,1 por ciento. En relación a los pacientes con parálisis cerebral señalamos la alta frecuencia de fracturas dentales registrándose un 30 por ciento de dientes afectados. Nuestros resultados confirman de nuevo la alta prevalencia de anomalías dentarias, sobre todo agenesias y anomalías de oclusión en los pacientes con minusvalías psíquicas. También señalamos la alta frecuencia de traumatismos dentales en pacientes con parálisis cerebral (AU)

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Estudio epidemiológico del estado de salud oral en una población de adultos discapacitados psíquicos: Parte II. Estudio comparativo de pacientes con síndrome de Down y otras minusvalías psíquicas / Epidemiological variables of oral health in handicapped adults: Part II. Diferences among Down syndrome patients and other handicapped adults patients

En él presente estudio, sé relaciona y compara los índices de caries, necesidades de tratamiento restaurador, estado periodontal, administración de flúor y el consumo de medicación antiepiléptica y tranquilizantes entre pacientes con síndrome de Down y con encefalopatías y oligofrenias. Se han explorado un total de 157 adultos con retraso mental leve-moderado, siendo un 44 por ciento de sujetos con encefalopatías un 09 por ciento con síndrome de Down y un 21,7 por ciento con oligofrenia . Los resultados obtenidos confirman que los índices de caries son significativamente (p menor 0.01 ) más altos para los grupos afectos de otras minusvalías que para el síndrome de Down, sin embargo hemos registrado mayor afectación periodontal para la encefalopatía y, oligofrenia, siendo significativo en estos grupos los que se medicaban con antiepilépticos a diferencia del síndrome de Down (4,2 por ciento). También encontramos relación significativa para el consumo de tranquilizantes. Registramos también diferencias significativas en la administración de colutorios de flúor, siendo mayor en el grupo dé oligofrenias. ",o encontramos diferencias significativas en relación con el sexo. Consideramos que fa prevalencia de caries en el síndrome de Down es más baja que el resto de minusválidos psíquicos estudiados y descartamos el factor, de retraso de la erupción como posible causa dé ésta disminución, dado el grupo de edad que hemos estudiado. Sin embargo si sugerimos, como posibles factores de asociación la medicación tranquilizante y antiepiléptica en estos grupos (AU)

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Estudio epidemiológico del estado de salud oral en una población de adultos discapacitados psiquicos: Parte I. Estudio descriptivo / Epidemiological variables of oral health in handicarpped adults: Part I

Se ha realizado un estudio descriptivo de caries, higiene oral y enfermedad periodontal en una población adulta no institucionalizada con minusvalías psíquicas. El total de explorados fueron f66 individuos, comprendidos entre 20-40 años de edad. La media obtenida para el ( AOD fue de un 5,97. Un 39,8 por ciento de sujetos se encontraban libres de caries presentes. siendo el componente de ausencia por caries de un 52,2 por ciento y ausentes por otras razones de un 21,7 por ciento . El componente obturado fue bajo siendo fas necesidades de obturación altas. La ausencia de higiene oral en estos sujetos fue mayor (28,3 por ciento) para el grupo de mayor edad registrándose una alta afectación periodontal y necesidades de tratamiento para este colectivo. Se compara la efectividad de Ios colutorios de flúor en el grupo que los realizada (n-117) de los que no (n- 49), no encontrando diferencias significativas (p>0.05). El porcentaje de sujetos que requieren cuidados dentales es alto, pero esto no es suficiente sino que esta población debería además ser incluidas en programas (..) (AU)

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Estudio epidemiológico de salud bucodental y necesidades de tratamiento en una población infantil, incluida en programa de un área básica de salud de la Comunidad de Madrid / Epidemic study of health and neccessities of treatment in an infantile population, incluyed in program of a basic area of health of the Comunidad de Madrid

El objetivo de este estudio. Es realizar un estudio descriptivo transversal de la situación bucodental en une población escolar ole 1166 niños comprendidos entre 6 y 15 años de edad correspondientes a un área básica (le salud de la comunidad de Madrid. integrada en un programa preventivo. Los índices de caries obtenidos en esta población fueron de: C.A.O.D.,1,5 ,C.A.O.S. I-9-. Ceod, 1),9. reos 1,5 y CAOM de 1,3. El índice de restauración alcanzó el 10,4 por ciento siendo las necesidades de tratamiento (le 1,7 obturaciones por niño. El l estudio (le la ATM no encontró patología en un 89 por ciento de los escolares (AU)

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Rehabilitación y valoración funcional de la artroplastia de hombro / Rehabilitation and functional evaluation of shoulder arthroplasty

Introducción: El recambio protésico de la articulación glenohumeral es más novedoso que los de cadera y rodilla, pero sus resultados no son tan brillantes. Pretendemos conocer las características de los pacientes intervenidos con esta técnica, valorar los resultados funcionales tras la rehabilitación y describir factores que influyen en ellos. Material y métodos: Revisamos 44 pacientes intervenidos entre enero de 1995 y mayo de 1998. Analizamos variables como sexo, edad, etiología, tipo de prótesis, procedimientos quirúrgicos asociados, tiempo de rehabilitación, movilidad alcanzada y complicaciones asociadas. En los de etiología traumática se han valorado los resultados funcionales mediante la escala de Constant. Para conocer los factores pronósticos hemos comparado los resultados funcionales según la edad, el estado del manguito de los rotadores y el tiempo de tratamiento rehabilitador. Resultados: La edad media ha sido de 66,7 años, con incidencia superior en mujeres (72,7 por ciento). La causa más frecuente fue la traumática. El tiempo medio de tratamiento rehabilitador fue de 20,3 semanas. Los resultados funcionales obtenidos en los casos traumáticos, malos en términos absolutos, mejoran al compararlos con los obtenidos en el hombro sano de los mismos pacientes. La edad es predictor de un buen resultado funcional. Conclusiones: Los resultados en cuanto rango de movilidad y fuerza son malos, sin embargo se consigue un eficaz control del dolor. Los pacientes de menor edad forman el grupo en que se obtienen mejores resultados (AU)