Anisotropic colloids through non-trivial buckling

We present a study on buckling of colloidal particles, including experimental, theoretical and numerical developments. Oil-filled thin shells prepared by emulsion templating show buckling in mixtures of water and ethanol, due to dissolution of the core in the external medium. This leads to conformations with a single depression, either axisymmetric or polygonal depending on the geometrical features of the shells. These conformations could be theoretically and/or numerically reproduced in a model of homogeneous spherical thin shells with bending and stretching elasticity, submitted to an isotropic external pressure.Comment: submitted to EPJ

Reproducible mini-slump test procedure for measuring the yield stress of cementitious pastes

The mini-slump test is a fast, inexpensive and widely adopted method for evaluating the workability of fresh cementitious pastes. However, this method lacks a standardised procedure for its experimental implementation, which is crucial to guarantee reproducibility and reliability of the test results. This study investigates and proposes a guideline procedure for mini-slump testing, focusing on the influence of key experimental (mixing and testing) parameters on the statistical performance of the results. The importance of preparation of always testing at the same time after mixing, testing each batch once rather than conducting multiple tests on a single batch of material, is highlighted. A set of alkali-activated fly ash-slag pastes, spanning from 1 to 75 Pa yield stresses, were used to validate the test method, by comparison of calculated yield stresses with the results obtained using a conventional vane viscometer. The proposed experimental procedure for mini-slump testing produces highly reproducible results, and the yield stress calculated from mini-slump values correlate very well with those measured by viscometer, in the case of fresh paste of pure shear flow. Mini-slump testing is a reliable method that can be utilised for the assessment of workability of cements

ECONOMIC ANALYSIS OF A LARGE SCALE ORAL VACCINATION PROGRAM TO CONTROL RACCOON RABIES

Since the late 1980s, results of oral vaccination trials in several states have provided growing evidence that this vaccination method may be effective for controlling the spread of rabies in raccoons (Procyon lotor). This study examines the economic feasibility of using oral vaccination on a larger scale than previous trials. We analyze the benefits and costs associated with a hypothetical barrier that would stretch from Lake Erie to the Gulf of Mexico, combining natural geographic features provided by the Appalachian Mountains with oral vaccination zones. The goal of this barrier would be to prevent the raccoon rabies variant from moving west into broader geographic regions of the United States. The costs of establishing and maintaining this hypothetical barrier are compared to the avoided costs of not having to live with raccoon rabies west of its current distribution. The westward advance of raccoon rabies, if it is not contained, is projected using simple models based on constant rates of spread. Our results show that preventing the westward movement of raccoon rabies by combining an oral vaccination program with natural barriers may be economically feasible. Discounted costs of establishing and maintaining the barrier are estimated to total between US$58 million and US$148 million. Net benefits of program implementation range between US$48 million and US$496 million for a variety of models, including ones that exclude forgone pet vaccination expenditures. The analysis also provides a framework for developing future models to explore the benefits and costs of eliminating raccoon rabies from currently affected areas