Stalk sap nitrate test as a potential tool for nitrogen fertilizer recommendations for maize
Not Available
Mahal, Navreet K.↗
Engineering topics
Dong, Liang
Publications and source records attributed to Dong, Liang.
Miniature sensors with probe insertable into and for obtaining measurements from plants and a variety of other mediums
Apparatus, methods, and systems for transducing measurements from medium of interest. One non-limiting example is in planta monitoring of plants. In one aspect, a micro- or nano-scale probe body includes one or more microprobes (e.g. microneedles or waveguides) to access desired plant tissue, and one or more microsensors on the probe body. A microcircuit on or in the probe body transduces relevant measurements from the microsensor(s). An output interface allows storage, communication, or transfer of the transduced measurement for further use. Non-limiting examples are processing into estimations of chemical concentrations or the like for biochemical sensing. As such, if used as in planta sensors, they can be minimally invasive and cost effective for both single use and use in sets for plural plants with one central station.
Dong, Liang↗
Self-contained, automated, long-term sensor system for monitoring of soil and water nutrients in fields
An automated, fieldable ion-selective sensor system for frequent detection of nutrients in soils or water is set forth. In one aspect, an integrated small form-factor housing includes a battery, processor, a fluid manipulation unit and reservoirs, and a chemical species detection cell. A flow-through sampling head can be connected to the detection cell and a waste reservoir by flexible tubing sealingly connected at opposite ends of the tube. In one aspect, improved performance of the ion-selective sensor includes adding an ion-to-electron transfer interlayer between an ion-selective membrane and its working electrode. In one aspect, the sensor is solid-state and uses printed polymeric composite of POT-MoS$_{2}$. The use of a porous tube for a sampling head and fluid connection at opposite ends allows not only fluid to be removed from the head to the detection cell for measurement but also flow in an opposite direction and out to a waste reservoir to clean and reset for a next sample measurement.
60 APPLIED LIFE SCIENCES↗
Relationship of Chemical Composition and Moisture Sensitivity in LiNi x Mn y Co 1-x-y O 2 for Lithium-Ion Batteries
Chemical composition–moisture sensitivity relationship of LiNi x Mn y Co 1-x-y O 2 (NMC) cathode materials was investigated by exploring crystal structures, surface properties, and electrochemical performance behaviors of various commercial NMC powders: LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC111), LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC532), LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622), and LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811). The NMC powders were stored in different moisture conditions: moisture-free, humidified air, or immersed in water. Rietveld refinement analysis of X-ray diffraction (XRD) data and scanning electron microscopy (SEM) were used to characterize the crystal structure changes and the evolution of particle surfaces morphologies. The effect of moisture contamination on the electrochemical properties of NMC cathodes was studied by galvanostatic cycling and electrochemical impedance spectroscopy (EIS). The moisture contamination resulted in either structural disorder or unwanted surficial deposition products, which increased a charge-transfer impedance and consequent performance degradation of battery cells. The results showed that NMC’s moisture vulnerability increased with Ni content (x) despite protective coatings on commercial particles, which stressed the necessity of alternative surface passivation strategies of Ni-rich NMC for broad applications such as electric vehicles and electrified aircraft propulsion.
25 ENERGY STORAGE↗
Miniature sensors with probe insertable into and for obtaining measurements from plants and a variety of other mediums
Apparatus, methods, and systems for transducing measurements from a medium of interest. One non-limiting example is in planta monitoring of plants. In one aspect, a micro- or nano-scale probe body includes one or more microprobes (e.g. microneedles or waveguides) to access desired plant tissue, and one or more microsensors on the probe body. A microcircuit on or in the probe body transduces relevant measurements from the microsensor(s). An output interface allows storage, communication, or transfer of the transduced measurement for further use. Non-limiting examples are processing into estimations of chemical concentrations or the like for biochemical sensing. As such, if used as in planta sensors, they can be minimally invasive and cost effective for both single use and use in sets for plural plants with one central station.
Dong, Liang↗
Phenethylammonium Functionalization Enhances Near-Surface Carrier Diffusion in Hybrid Perovskites
Understanding semiconductor surface properties and manipulating them chemically are critical for improving their performance in optoelectronic devices. Hybrid halide perovskites have emerged as an exciting class of highly efficient solar materials; however, their device performance could be limited by undesirable surface properties that impede carrier transport and induce recombination. Here we show that surface functionalization of methylammonium lead iodide (MAPbI 3 ) perovskite with phenethylammonium iodide (PEAI), a commonly employed spacer cation in two-dimensional perovskites, can enhance carrier diffusion in the near-surface regions and reduce defect density by more than one order of magnitude. Using transient transmission and reflection microscopy, we selectively imaged the transport of the carriers near the (001) surface and the bulk carriers in single-crystal MAPbI 3 microplates. The surface functionalization increases the diffusion coefficient of the carriers in a 40-nm subsurface region from ~ 0.6 cm 2 s -1 to ~ 1 cm 2 s -1 , similar to the value for bulk carriers. These results suggest the PEA ligands are effective in suppressing surface defect and phonon scattering and shed light on the mechanisms for enhancing photophysical properties and improving solar cell efficiency.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Berry Phase Effects in Dipole Density and the Mott Relation
Here, we provide a unified semiclassical theory for thermoelectric responses of any observable represented by an operator $\hat{θ}$ that is well defined in periodic crystals. The Einstein and Mott relations are established generally in the presence of Berry phase effects for various physical realizations of $\hat{θ}$ in electronic systems, including the familiar case of the electric current as well as the currently controversial cases of the spin polarization and spin current. The magnetization current, which has been proven indispensable in the thermoelectric response of electric current, is generalized to the cases of various $\hat{θ}$. In our theory the dipole density of a physical quantity emerges and plays a vital role, which contains not only the statistical sum of the dipole moment of $\hat{θ}$ but also a Berry phase correction.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Toward Ultralight High Strength Structural Materials via Collapsed Carbon Nanotube Bonding
The growing commercial availability of carbon nanotube (CNT) macro-assemblies such as sheet and yarn is making their use in structural composite components increasingly feasible. However, the mechanical properties of these materials continue to trail those of state-of-the-art carbon fiber composites due to relatively weak inter-tube load transfer. Forming covalent links between adjacent CNTs promises to mitigate this problem, but it has proven difficult in practice to introduce them chemically within densified and aligned CNT materials due to their low permeability. To avoid this limitation, this work explores the combination of pulsed electrical current, temperature, and pressure to introduce inter-CNT bonds. Reactive molecular dynamics simulations identify the most probable locations, configurations, and conditions for inter-nanotube bonds to form. This process is shown to introduce covalent linkages within the CNT material that manifest as improved macroscale mechanical properties. The magnitude of this effect increases with increasing levels of prealignment of the CNT material, promising a new synthesis pathway to ultralight structural materials with specific strengths and stiffnesses exceeding 1 and 100 GPa/(g/cu.cm), respectively.
Jensen, Benjamin D.↗