Effects of coupled heat and moisture and load damage on chloride transport in concrete

This paper presents a thoroughgoing research on chloride transport in damaged concrete. Effects of temperature and temperature gradient on chloride transport was investigated along with effects of relative humidity, humidity gradient, concrete damage and exposure time. The higher the temperature and the greater the humidity gradient were, the quicker chloride transport was. Moisture transport increased as concrete damage increased, while chloride transport decreased incrementally. Considering the effect of coupled heat and moisture on chloride transport in concrete, a chloride transport model was established and verified by experiments. Chloride profiles in damaged concrete were related to temperature, temperature gradient, relative humidity and humidity gradient. The chloride attack rate decreased with increasing concrete damage and exposure time. Hence, coupled heat and moisture as well as concrete damage had significant effects on chloride transport in damaged concrete, and effects of concrete damage on chloride transport should be considered when determining chloride profiles in damaged concrete.

Study on Surface and Internal Humidity of Dunes in the Southwestern Margin of the Taklimakan Desert

Greening on the edge of desert is an effective way to prevent and control desertification. This paper studies the humidity characteristics of sand samples collected from the surface and interior of dunes in the southwestern edge of the Taklimakan Desert, whose geographic coordinates are 39°43’37” – 39°43’41” N, 78°43’02” – 78°43’09” E. The humidity of sand samples at vertical depths under five different surface positions of windward slope bottom, windward slope middle, windward slope top, leeward slope middle and leeward slope bottom was studied. On the surface of the sand at different locations and at the same depth under the surface, the sand humidity is greater closer to the bottom of the slope, for both windward slope and leeward slope. The humidity gradient values on the surface and at different depths on different positions of the dunes are obtained. Finally, recommendations are provided for effective ways to prevent desertification in the desert edge of Kashgar.

Preferential Root Tropisms in 2D Wet Granular Media with Structural Inhomogeneities

We investigate certain aspects of the physical mechanisms of root growth in a granular medium and how these roots adapt to changes in water distribution induced by the presence of structural inhomogeneities in the form of solid intrusions. Physical intrusions such as a square rod added into the 2D granular medium maintain robust capillary action, pumping water from the more saturated areas at the bottom of the cell towards the less saturated areas near the top of the cell while the rest of the medium is slowly devoid of water via evaporation. The intrusion induces “preferential tropism” of roots by first generating a humidity gradient that attracts the root to grow towards it. Then it guides the roots and permits them to grow deeper into more saturated regions in the soil. This further allows more efficient access to available water in the deeper sections of the medium thereby resulting to increased plant lifetime.

Effects of Soil Moisture on the Longitudinal Dryline Position in the Southern Great Plains

The dryline is among the most important meteorological phenomena in the Great Plains because of its significance in tornadogenesis, severe weather, and consistent rainfall. Past research has extensively examined the dynamics of the dryline; however, recent meteorological research looks beyond dynamics and focuses on land–atmosphere interactions. This study focuses on how soil moisture, a surrogate for evapotranspiration, affects the climatological longitudinal positioning of the dryline, presenting a climatological study for the months of April–June during 2006–15 in the southern Great Plains. Here, drylines are defined as specific humidity gradients exceeding 3 g kg−1 (100 km)−1 that do not deviate more than 30° from a north–south orientation; they were found to occur on 33.4% of spring days, and the most favorable position was −100.9° at 0000 UTC. Specific humidity gradients ranged from 3.0 to 15.2 g kg−1 (100 km)−1, with an average value of 6.8 g kg−1 (100 km)−1. A relationship between the dryline longitudinal position and soil moisture was found; as soil moisture values increased, the dryline was located farther west, which suggests soil moisture may influence the longitudinal positioning of the dryline. There was also a relationship between the gradient of soil moisture and the intensity (specific humidity gradient) of the dryline, such that when longitudinal soil moisture gradients were strong (increasing from west to east), the dryline intensity increased.

Graphene oxide based moisture-responsive biomimetic film actuators with nacre-like layered structures

Hygroresponsive biomimetic actuators that convert chemical potential energy contained within the humidity gradient into mechanical deformation are of particular significance for realizing a sustainable society.

Mussel inspired locomotive: the moisture induced actuation in a poly(vinyl alcohol) film containing melanin-like dopamine nano spheres

We report here for the first time a PVA film incorporated with PDNs that is capable of fast and perpetual motion driven by a humidity gradient.