Tethered Balloon System Leaf Wetness Sensor
Leaf wetness sensor measurements from the tethered balloon system.
54 ENVIRONMENTAL SCIENCES↗
Engineering topics
Shi, Yan
Publications and source records attributed to Shi, Yan.
More sustainable electricity generation in hot and dry fuel cells with a novel hybrid membrane of Nafion/nano-silica/hydroxyl ionic liquid
Here, a new hybrid proton exchange membrane (PEM) has been prepared from hydroxyl functionalized imidazolium ionic liquid (IL-OH), Nafion and nano-SiO 2 . The IL-OH, with a hydroxyl group that acts as both a proton acceptor and donor, forms strong hydrogen bonds with both Nafion and nano-SiO 2 , resulting in an effective hydrogen bond network in the ternary membrane. Such an anhydrous hydrogen-bond network, which is unknown previously, endows the PEMs with higher proton conductivity, greater thermal stability and surprisingly a more robust mechanical performance than PEMs consisting of conventional ionic liquids. The resulting PEMs have a tensile strength that is more than twice as strong as recast Nafion and an anhydrous ionic conductivity of ~55 mS cm –1 at temperatures above 160 °C, with a proton transfer number of ~0.9. A laboratory assembled H 2 –O 2 fuel cell employing this new PEM delivered a power density of 340 and 420 mW cm –2 at 160 and 180 °C, respectively.
25 ENERGY STORAGE↗
Controlled Mechanical Buckling for Origami-Inspired Construction of 3D Microstructures in Advanced Materials
Origami is a topic of rapidly growing interest in both the scientific and engineering research communities due to its promising potential in a broad range of applications. Previous assembly approaches of origami structures at the micro/nanoscale are constrained by the applicable classes of materials, topologies and/or capability of control over the transformation. In this work, we introduce an approach that exploits controlled mechanical buckling for autonomic origami assembly of 3D structures across material classes from soft polymers to brittle inorganic semiconductors, and length scales from nanometers to centimeters. This approach relies on a spatial variation of thickness in the initial 2D structures as an effective strategy to produce engineered folding creases during the compressive buckling process. The elastic nature of the assembly scheme enables active, deterministic control over intermediate states in the 2D to 3D transformation in a continuous and reversible manner. Demonstrations include a broad set of 3D structures formed through unidirectional, bidirectional, and even hierarchical folding, with examples ranging from half cylindrical columns and fish scales, to cubic boxes, pyramids, starfish, paper fans, skew tooth structures, and to amusing system-level examples of soccer balls, model houses, cars, and multifloor textured buildings.
36 MATERIALS SCIENCE↗
Evaluation of long-term surface-retrieved cloud droplet number concentration with in situ aircraft observations
A new cloud-droplet number concentration (NDROP) value added product (VAP) has been produced at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site for the 13 years from January 1998 to January 2011. The retrieval is based on surface radiometer measurements of cloud optical depth from the multi-filter rotating shadow-band radiometer (MFRSR) and liquid water path from the microwave radiometer (MWR). It is only applicable for single-layered warm clouds. Validation with in situ aircraft measurements during the extended-term aircraft field campaign, Routine ARM Aerial Facility (AAF) CLOWD Optical Radiative Observations (RACORO), shows that the NDROP VAP robustly reproduces the primary mode of the in situ measured probability density function (PDF), but produces a too wide distribution, primarily caused by frequent high cloud-droplet number concentration. Our analysis shows that the error in the MWR retrievals at low liquid water paths is one possible reason for this deficiency. Modification through the diagnosed liquid water path from the coordinate solution improves not only the PDF of the NDROP VAP but also the relationship between the cloud-droplet number concentration and cloud-droplet effective radius. Consideration of entrainment effects rather than assuming an adiabatic cloud improves the values of the NDROP retrieval by reducing the magnitude of cloud-droplet number concentration. Aircraft measurements and retrieval comparisons suggest that retrieving the vertical distribution of cloud-droplet number concentration and effective radius is feasible with an improvement of the parameter representing the mixing effects between environment and clouds and with a better understanding of the effect of mixing degree on cloud properties.
54 ENVIRONMENTAL SCIENCES↗
Wireless Optofluidic Systems for Programmable In Vivo Pharmacology and Optogenetics
Not Available
60 APPLIED LIFE SCIENCES↗
Conformal piezoelectric systems for clinical and experimental characterization of soft tissue biomechanics
Mechanical assessment of soft biological tissues and organs has broad relevance in clinical diagnosis and treatment of disease. Existing characterization methods are invasive, lack microscale spatial resolution, and are tailored only for specific regions of the body under quasi-static conditions. Here, we develop conformal and piezoelectric devices that enable in vivo measurements of soft tissue viscoelasticity in the near-surface regions of the epidermis. Furthermore, these systems achieve conformal contact with the underlying complex topography and texture of the targeted skin, as well as other organ surfaces, under both quasi-static and dynamic conditions. Experimental and theoretical characterization of the responses of piezoelectric actuator–sensor pairs laminated on a variety of soft biological tissues and organ systems in animal models provide information on the operation of the devices. Studies on human subjects establish the clinical significance of these devices for rapid and non-invasive characterization of skin mechanical properties.
36 MATERIALS SCIENCE↗
CDK4-mediated MnSOD activation and mitochondrial homeostasis in radioadaptive protection
Not Available
Jin, Cuihong↗
ld (b1)
A laser disdrometer (LDIS) measures the drop size spectra and fall velocity of hydrometeors during precipitation events. The passage of hydrometeors through a horizontal area positioned between an eye-safe laser and an array detector results in blockage of the laser beam in proportion to the size of the drop or particle. In addition to drop/particle size and fall speed, precipitation type is classified. ARM also deploys video disdrometers (VDIS).
54 ENVIRONMENTAL SCIENCES↗
Temperature- and size-dependent characteristics in ultrathin inorganic light-emitting diodes assembled by transfer printing
Favorable temperature- and size-dependent device characteristics in mechanically flexible, thin (~6.45 μm thick), microscale inorganic InGaN/GaN-based light-emitting diodes enable their use as highly efficient, robust devices that are capable of integration on diverse classes of unconventional substrates, including sheets of plastic. Here, finite element analysis and systematic studies of the operational properties establish important thermal, electrical, and optical considerations for this type of device.
42 ENGINEERING↗
Arylsulfonamidopiperidone derivatives as a novel class of factor Xa inhibitors
Abstract not provided
Shi, Yan↗