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Clothing microclimates, i.e. the space between the skin and the clothing, can play a central role in the heat and mass exchanges from or to the body. This is especially true for protective clothing, where microclimates are generally thicker and natural convection is more likely to occur. We used a computational fluid dynamics approach to perform numerical studies of fluid flow and heat transfer across cylindrical clothing microclimates for Reynolds number of 3900. Transient simulations were performed for three different values of microclimate thickness to diameter ratio (0.05, 0.10 and 0.25), considering a two-dimensional cross-section of a human limb surrounded by a porous fabric and exposed to cool external air ( 10 ° C ). The obtained local heat transfer along the skin shows that increasing the microclimate thickness ratio from 0.05 to 0.25 decreases the convective heat fluxes by up to 100 % in the upstream regions of the microclimate, and increases them up to 190 % in the downstream regions. This asymmetry, which indicates an increasingly important role of natural convection as the microclimate thickness ratio is increased, is often overlooked in space-averaged approaches due to the opposite changes in the different regions of the microclimate. Local variations in temperature along the outer fabric and in convective fluxes along the skin were significant, reaching up to 14 K and 90%, respectively. The critical thickness ratio above which natural convection should not be ignored was found to be 0.1 (e.g. corresponding to a microclimate thicknesses of 11 mm or 8 mm, around an upper arm or forearm, respectively).

Clothing plays a key role in the capacity of the body to adapt to the surrounding thermal environments. Thus, it is critically important to have a solid understanding of the effects of clothing and fibres properties on the body exchange rates. To this end, a detailed transfer model was implemented to analyse the effect of several textiles characteristics (outer surface emissivity, tortuosity, and fraction of fibre) and fibre properties (affinity with water, coefficient of water diffusion in the fibres, thermal conductivity, density, and specific heat), on the heat and mass transfer through multilayer clothing, for different intensities of heat/sweat release. The temperature and humidity predictions were validated with experimental data obtained during measurements of textile evaporative resistance. The results obtained for the multilayer clothing during an energy-demanding activity (i.e. metabolic heat production of 300 W m(-2) and sweating of 240 g m(-3) h(-1)) show that a decrease in the emissivity of the outer surface (0.9 - 0.1), and an increase in the coefficient of water diffusion in the fibres of the inner layer (4 x 10(-16) - 4 x 10(-11)), induce an increase in the maximum skin temperature (of 4.5 degrees C and 6.8 degrees C, respectively). Moreover, the water trapped inside clothing is significantly increased by augmenting the fraction of fibre (0.07 - 0.4), the density of the fibre (910 - 7850 kg m(3)), the fibre affinity with water (i.e. regains of 0.07 - 0.3), and the coefficient of water diffusion in the fibres (4 x 10(-16) - 4 x 10(-11)). During the post-exercise phase (with metabolic heat production of 65 W m(-2) and perspiration of 9 g m(-3) h(-1)), the parameters affecting significantly the Water content of the inner layer are the fraction of fibre, its density, and its affinity with water. The proposed numerical approach allows the study of strategies to optimise heat/mass transport rates through materials surrounding the body (e.g. in clothing applications, automotive environments or work-place microclimates) in order to minimise thermal discomfort and/or problems of high water content (e.g. friction burns and/or growth of fungi and bacteria).

To date, crystallization studies conducted in space laboratories, which are prohibitively costly and unsuitable to most research laboratories, have shown the valuable effects of microgravity during crystal growth and morphogenesis. Herein, an easy and highly efficient method is shown to achieve space-like experimentation conditions on Earth employing custom-made microfluidic devices to fabricate 2D porous crystalline molecular frameworks. It is confirmed that experimentation under these simulated microgravity conditions has unprecedented effects on the orientation, compactness and crack-free generation of 2D porous crystalline molecular frameworks as well as in their integration and crystal morphogenesis. It is believed that this work will provide a new "playground" to chemists, physicists, and materials scientists that desire to process unprecedented 2D functional materials and devices., Advanced Materials, 33 (30), ISSN:0935-9648, ISSN:1521-4095

The aim of this study was to develop methodologies and experimental procedures to determine textile parameters required in numerical approaches of heat and mass transfer through textiles. Privileging techniques usually available in textile/clothing laboratories, experimental approaches were defined that allow to estimate all required parameters, while taking into consideration water presence in the fibres and hence the effect of fibres hygroscopic properties. Numerical models usually require values of textile thickness, fibre fraction, and tortuosity, as well as knowledge of the boundary conditions, e.g. convective heat and mass transfer coefficients. To calculate these parameters, thickness, weight, and volume of textile samples were measured, whereas convective and textile evaporative resistances were determined by indirect measurements. Results were obtained for four distinct textile samples (made of wool, cotton, and a mixture of materials), of different hydrophilic nature. When the obtained parameters were incorporated in a numerical model and numerical predictions of temperature and humidity were compared with experimental data obtained during measurements of fabric evaporative resistance, it was shown that the predictions were accurate; this lends support to the developed methods and approaches. Since an uncertainty in the measured parameters can compromise the accuracy of numerical predictions, a sensitivity analysis was conducted to study the influence of deviations in the model input parameters and of assumptions regarding water presence in the fibres, on the predictions of heat and mass transfer rates. The results show that a deviation in textile weight and thickness as well as the assumption of no water retained in fibres during their characterisation, have a significant effect on the predicted heat transfer and water distribution over time. Moreover, a deviation in the total evaporative resistance, convective evaporative resistance, and sorption rate factor has great influence on the heat flux obtained in the initial period of testing.

A methodology that can be efficiently used to synthesize, isolate, and study out-of-equilibrium crystal structures employing controlled and diffusion-limited microfluidic environments is demonstrated. Unlike studies conducted with conventional mixing procedures in a flask, it is proven experimentally and with numerical simulations that microfluidic technologies can undoubtedly fine-tune reaction times and reagents concentration profiles; factors that enable out-of-equilibrium crystal forms to be obtained., The authors acknowledge the financial support from MINECO-Spain, under projects MAT2012-30994 and CTQ2011-16009-E, the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement no 615954 and from the Swiss National Science Foundation (SNF) through the project no 200021_160174. The authors thank the Microscopy Service of the UAB. M.R.-M. and C.C. thank the ICN2 for their research fellowship, I.I., N.D., and J.P.-L. thank the MINECO for RyC contracts. ICN2 acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program, under Grant SEV-2013-0295.

The optimisation of the performance of products with smart/active functionalities (e. g. in protective clothing, home textiles products, automotive seats, etc.) is still a challenge for manufacturers and developers. The aim of this study was to optimise the thermal performance of a heating product by a numerical approach, by analysing several opposing requirements and defining solutions for the identified limitations, before the construction of the first prototype. A transfer model was developed to investigate the transport of heat from the skin to the environment, across a heating blanket with an embedded smart heating system. Several parameters of the textile material and of the heating system were studied, in order to optimise the thermal performance of the heating blanket. Focus was put on the effects of thickness and thermal conductivity of each layer, and on parameters associated with the heating elements, e.g. position of the heating wires relative to the skin, distance between heating wires, applied heating power, and temperature range for operation of the heating system. Furthermore, several configurations of the blanket (and corresponding heating powers) were analysed in order to minimise the heat loss from the body to the environment, and the temperature distribution along the skin. The results show that, to ensure an optimal compromise between the thermal performance of the product and the temperature oscillation along its surface, the distance between the wires should be small (and not bigger than 50 mm), and each layer of the heating blanket should have a specific thermal resistance, based on the expected external conditions during use and the requirements of the heating system (i.e. requirements regarding energy consumption/efficiency and capacity to effectively regulate body exchanges with surrounding environment). The heating system should operate in an ON/OFF mode based on the body heating needs and within a temperature range specified based on the blanket total thermal resistance, external temperature during use, and observed temperature on the blanket outer surface (safety and energy efficiency aspects). The approach described in this work enabled the definition of the textile properties, the features of the embedded heating system, and the overall design of the system thus reducing substantially the number of prototypes needed for the final performance optimisation and fine-tuning.