In this study, we performed a conceptual modeling on solute transport based on theoretical stream tube model (STM) with various travel time distributions assuming a pure convective flow through each tube in order to i...In this study, we performed a conceptual modeling on solute transport based on theoretical stream tube model (STM) with various travel time distributions assuming a pure convective flow through each tube in order to investigate how the lengths and distributions of solute travel time through STM affect the breakthrough curves at the end mixing surface. The conceptual modeling revealed that 1) the shape of breakthrough curve (BTC) at the mixing surface was determined by not only input travel time distributions but also solute injection mode such as sampling time and pulse lengths;2) the increase of pulse length resulted in the linear increase of the first time moment (mean travel time) and quadratic increase of the second time moment (variance of travel time) leading to more spreading of solute, however, the second time moment was not affected by travel time distributions and 3) for a given input distributions the increase in travel distance resulted in more dispersion with the quadratic increase of travel time variance. This indicates that stream tube model obeying strictly pure convective flow follows the concept of convective-lognormal transport (CLT) model regardless the input travel time distributions.展开更多
Stretchable and conformal humidity sensors that can be attached to the human body for continuously monitoring the humidity of the environment around the human body or the moisture level of the human skin can play an i...Stretchable and conformal humidity sensors that can be attached to the human body for continuously monitoring the humidity of the environment around the human body or the moisture level of the human skin can play an important role in electronic skin and personal healthcare applications. However, most stretchable humidity sensors are based on the geometric engineering of non-stretchable components and only a few detailed studies are available on stretchable humidity sensors under applied mechanical deformations. In this paper, we propose a transparent, stretchable humidity sensor with a simple fabrication process, having intrinsically stretchable components that provide high stretchability, sensitivity, and stability along with fast response and relaxation time. Composed of reduced graphene oxide-polyurethane composites and an elastomeric conductive electrode, this device exhibits impressive response and relaxation time as fast as 3.5 and 7 s, respectively. The responsivity and the response and relaxation time of the device in the presence of humidity remain almost unchanged under stretching up to a strain of 60% and after 10,000 stretching cycles at a 40% strain. Further, these stretchable humidity sensors can be easily and conformally attached to a finger for monitoring the humidity levels of the environment around the human body, wet objects, or human skin.展开更多
文摘In this study, we performed a conceptual modeling on solute transport based on theoretical stream tube model (STM) with various travel time distributions assuming a pure convective flow through each tube in order to investigate how the lengths and distributions of solute travel time through STM affect the breakthrough curves at the end mixing surface. The conceptual modeling revealed that 1) the shape of breakthrough curve (BTC) at the mixing surface was determined by not only input travel time distributions but also solute injection mode such as sampling time and pulse lengths;2) the increase of pulse length resulted in the linear increase of the first time moment (mean travel time) and quadratic increase of the second time moment (variance of travel time) leading to more spreading of solute, however, the second time moment was not affected by travel time distributions and 3) for a given input distributions the increase in travel distance resulted in more dispersion with the quadratic increase of travel time variance. This indicates that stream tube model obeying strictly pure convective flow follows the concept of convective-lognormal transport (CLT) model regardless the input travel time distributions.
文摘Stretchable and conformal humidity sensors that can be attached to the human body for continuously monitoring the humidity of the environment around the human body or the moisture level of the human skin can play an important role in electronic skin and personal healthcare applications. However, most stretchable humidity sensors are based on the geometric engineering of non-stretchable components and only a few detailed studies are available on stretchable humidity sensors under applied mechanical deformations. In this paper, we propose a transparent, stretchable humidity sensor with a simple fabrication process, having intrinsically stretchable components that provide high stretchability, sensitivity, and stability along with fast response and relaxation time. Composed of reduced graphene oxide-polyurethane composites and an elastomeric conductive electrode, this device exhibits impressive response and relaxation time as fast as 3.5 and 7 s, respectively. The responsivity and the response and relaxation time of the device in the presence of humidity remain almost unchanged under stretching up to a strain of 60% and after 10,000 stretching cycles at a 40% strain. Further, these stretchable humidity sensors can be easily and conformally attached to a finger for monitoring the humidity levels of the environment around the human body, wet objects, or human skin.
