Interfacial Tensions near Critical Endpoints: Experimental Checks of EdGF Theory

Predictions of the extended de Gennes-Fisher local-functional theory for the universal scaling functions of interfacial tensions near critical endpoints are compared with experimental data. Various observations of the binary mixture isobutyric acid $+$ water are correlated to facilitate an analysis of the experiments of Nagarajan, Webb and Widom who observed the vapor-liquid interfacial tension as a function of {\it both} temperature and density. Antonow's rule is confirmed and, with the aid of previously studied {\it universal amplitude ratios}, the crucial analytic ``background'' contribution to the surface tension near the endpoint is estimated. The residual singular behavior thus uncovered is consistent with the theoretical scaling predictions and confirms the expected lack of symmetry in $(T-T_c)$. A searching test of theory, however, demands more precise and extensive experiments; furthermore, the analysis highlights, a previously noted but surprising, three-fold discrepancy in the magnitude of the surface tension of isobutyric acid $+$ water relative to other systems.Comment: 6 figure

Composition profile of a wetting film in a binary mixture

The composition profile at a solid surface in the one phase region of a binary liquid mixture in the complete wetting regime has been studied with neutron reflectometry. A hexane rich film adsorbs to an octadecyl coated silicon surface from a n hexane d 14 perfluoro n hexane mixture. Above the critical temperature, T c, of 14.4 degrees C, there is a comparatively thin 5 20 nm film with an excess n hexane content that decays exponentially toward the bulk, with the n hexane content and decay length increasing as the temperature approaches T c. Below T c, as the coexistence temperature T 0 of 8.9 degrees C is approached, a very long range effect on the density profile becomes apparent and the n hexane content of the film remains greater than that of bulk out to distances z gt; 100 nm. Although the data are consistent with a z 3 decay of the composition profile, as expected for van der Waals forces, we cannot unambiguously assign a decay to the long range 80 120 nm region of the film. However, as for van der Waals forces, the n hexane surface excess, Gamma, increases as T T 0 1 3 near coexistence, but more steeply closer to T

Recent advances in the study of chemical surfaces and interfaces by specular neutron reflection

The use of specular neutron reflection to study a wide variety of problems in surface and interfacial chemistry is introduced and discussed. Recent developments in neutron reflectometry instrumentation, and their implementation in the design of the SURF reflectometer at the ISIS pulsed neutron source, are described. The design of the SURF reflectometer has been optimised for the surface chemistry of soft matter and new experimental results that exploit the novel features of this second generation neutron reflectometer are presented and discussed in the context of the opportunities for future studies that the technique and the new instrumentation presents. The examples from the broad programme in surface chemistry include surfactant and polymer adsorption at the air/liquid and liquid/solid interfaces, adsorption at the liquid/liquid interface; Langmuir-Blodgett films and liquid crystalline alignment layers, thin solid polymer films and interfaces; liquid mixtures and in situ electrochemistry

Recent advances in the study of chemical surfaces and interfaces by specular neutron reflection

The use of specular neutron reflection to study a wide variety of problems in surface and interfacial chemistry is introduced and discussed. Recent developments in neutron reflectometry instrumentation, and their implementation in the design of the SURF reflectometer at the ISIS pulsed neutron source, are described. The design of the SURF reflectometer has been optimised for the surface chemistry of soft matter and new experimental results that exploit the novel features of this second generation neutron reflectometer are presented and discussed in the context of the opportunities for future studies that the technique and the new instrumentation presents. The examples from the broad programme in surface chemistry include surfactant and polymer adsorption at the air/liquid and liquid/solid interfaces, adsorption at the liquid/liquid interface; Langmuir-Blodgett films and liquid crystalline alignment layers, thin solid polymer films and interfaces; liquid mixtures and in situ electrochemistry

Thigh-length compression stockings and DVT after stroke

Controversy exists as to whether neoadjuvant chemotherapy improves survival in patients with invasive bladder cancer, despite randomised controlled trials of more than 3000 patients. We undertook a systematic review and meta-analysis to assess the effect of such treatment on survival in patients with this disease

The power of Web 2.0 storytelling to overcome knowledge sharing barriers

Through a narrative review of the literature, this paper seeks to explore the importance of Web 2.0 Storytelling for overcoming barriers to knowledge sharing. While storytelling has been traditionally addressed as a valuable lever for many knowledge sharing issues, more recently, Web 2.0 technologies are becoming essential in enabling employees to participate in the creation, sharing and diffusion of knowledge. However, the link between Web 2.0 Storytelling and barriers to knowledge sharing behavior remains quite unexplored in the extant literature. By filling this gap, we pose the first pillars to explain this connection. Overall, our conceptual framework reveals that, since knowledge is something that resides in people, the extensive use of ICT tools may be not sufficient to capture the organizational advantages of knowledge sharing, if the human dimension is neglected. With this in mind, the twofold nature of Web 2.0 storytelling emerges as a powerful tool to manage the most important barriers to knowledge sharing. Such evidence may have meaningful implications for both theory and practice