Applications of signal transduction and xerophytophysiology by exposing hypocotyls in organic peanut production

The AnM practices in peanut production included three steps. The three letters, A, n and M, showed the shapes of the section-cross of the ridge at the three steps of different growth stages of the peanut crop. First, the peanut seeds were sown a little deeper than usual, about 8 cm, in the ridge to induce the extra-elongation of the hypocotyl. When the seeds were sown, the cross-section of the ridge looked like the letter “A”. The second, the hypocotyls elongated more than usual were exposed to light and dry air by removing the soil away around the young seedlings just after the emergence. At this time, the cross-section of the ridge looked like the letter “n”. The third, at the middle growth stages, soils on the both sides of ridge were earthed up to welcome the late pegs. At this time, the cross-section of the ridge looked like the letter “M”. Physiologically, the AnM technique induced osmotic adjustment, which improved photosynthetic activities by maintaining a higher leaf turgor potential. Anthocyanin accumulation was observed visually in hypocotyls of the young seedlings soon after the hypocotyl exposure started. The anthocyanin accumulation is accompanied by accumulations of soluble sugars, soluble proteins. All the consequences of the xerophytophysiological responses collaborated together to make the crop healthier through their individual function in plant growth and development. Gdi-15 (Groundnut desiccation induced) gene is a stress-responsive gene in peanut plant and its up-regulation expression was found in hypocotyl. In overall, hypocotyl exposure as a stimulation did induce the up-expression of the drought responsive gene, Gdi-15, and the consequent osmotic adjustment and anthocyanin accumulation but caused no damage to the whole plant. The AnM practice was more effective in the soil with compost applied to the surface layer and therefore it is feasible in organic peanut production

Thermal Conductivity of Chirality-Sorted Carbon Nanotube Networks

The thermal properties of single-walled carbon nanotubes (SWNTs) are of significant interest, yet their dependence on SWNT chirality has been, until now, not explored experimentally. Here, we used electrical heating and infrared thermal imaging to simultaneously study thermal and electrical transport in chirality-sorted SWNT networks. We examined solution processed 90% semiconducting, 90% metallic, purified unsorted (66% semiconducting), and as-grown HiPco SWNT films. The thermal conductivities of these films range from 80 to 370 W m-1 K-1 but are not controlled by chirality, instead being dependent on the morphology (i.e., mass and junction density, quasi-alignment) of the networks. The upper range of the thermal conductivities measured is comparable to that of the best metals (Cu and Ag), but with over an order of magnitude lower mass density. This study reveals important factors controlling the thermal properties of light-weight chirality-sorted SWNT films, for potential thermal and thermoelectric applications

High Field Breakdown Characteristics of Carbon Nanotube Thin Film Transistors

The high field properties of carbon nanotube (CNT) network thin film transistors (CN-TFTs) are important for their practical operation, and for understanding their reliability. Using a combination of experimental and computational techniques we show how the channel geometry (length LC and width WC) and network morphology (average CNT length Lt and alignment angle distribution θ) affect heat dissipation and high field breakdown in such devices. The results suggest that when WC ≥ Lt, the breakdown voltage remains independent of WC but varies linearly with LC. The breakdown power varies almost linearly with both WC and LC when WC Lt. We also find that the breakdown power is more susceptible to the variability in the network morphology compared to the breakdown voltage. The analysis offers new insight into the tunable heat dissipation and thermal reliability of CN-TFTs, which can be significantly improved through optimization of the network morphology and device geometry

Graphene-Based Electromechanical Thermal Switches

Thermal management is an important challenge in modern electronics, avionics, automotive, and energy storage systems. While passive thermal solutions (like heat sinks or heat spreaders) are often used, actively modulating heat flow (e.g. via thermal switches or diodes) would offer additional degrees of control over the management of thermal transients and system reliability. Here we report the first thermal switch based on a flexible, collapsible graphene membrane, with low operating voltage, < 2 V. We also employ active-mode scanning thermal microscopy (SThM) to measure the device behavior and switching in real time. A compact analytical thermal model is developed for the general case of a thermal switch based on a double-clamped suspended membrane, highlighting the thermal and electrical design challenges. System-level modeling demonstrates the thermal trade-offs between modulating temperature swing and average temperature as a function of switching ratio. These graphene-based thermal switches present new opportunities for active control of fast (even nanosecond) thermal transients in densely integrated systems

Thermal imaging and analysis of carbon nanotube composites

Carbon nanotube (CNT) films have a broad range of applications, from solar cells and transistors to bolometers and mechanical reinforcement additives for polymers. However, surprisingly little is still known about the thermal properties of such CNT films, and in particular about the intertube junctions. This study examines suspended films of conductive single-wall CNT (SWNT) films through electrical measurements and optical infrared (IR) thermometry in order to simultaneously characterize their electrical and thermal properties. Using an IR microscope, the real-time temperature profile of such CNT films under bias is mapped and used to extract thermal conductivity. A computation model was also developed to fit the one-dimensional heat diffusion equation to the temperature profile captured by the IR scope, including the effect of thermal contact resistance and heat loss to ambient. Transfer length method measurements were used to extract electrical contact resistance between the film and the electrodes. These methods were applied to investigate the properties of CNT films with several different morphologies, revealing that both electrical and thermal properties are strongly dependent on CNT volume density and junction within the films. Understanding fundamental transport within CNT networks allows us to try and decouple the properties and engineer novel materials for applications such as energy harvesting using thermoelectric power generation

ORGANIC POTATO CROPS ARE IMPROVED BY INOCULATING A MICROBIAL INOCULUM TO THE CUT SURFACE OF SEED TUBERS

Potato seed tubers are usually cut into blocks to reduce seed cost, break dormancy and induce dominance. In chemical farming, the cut surface is usually treated with fungicides to avoid infection. In the present research, the cut surface of the seed tuber blocks was treated with a microbial inoculum mixed into bamboo charcoal powder and dried for a moment. Inoculating and drying the cut trace of seed tuber blocks induced activation of the antioxidant enzymes SOD and POD. Properly drying the cut trace induced osmotic adjustment, leaf turgor improvement, disease resistance and yield increase in the potato crop. The treatments were more effective in the soil with compost applied onto the surface. The treatments with sterilized inoculum were more effective than that with the original inoculum. In conclusion, inoculating and properly drying cut trace of seed tuber blocks was feasible to improve organic potato crops

Transport and Thermopower in Graphene Transistors

Graphene is an exciting material for nanoelectronics research because of its excellent electrical and thermal properties. However, high-field transport and thermoelectric effects in graphene transistors are not yet well understood. This study introduces and tests the idea of manipulating the width of graphene transistors in order to change the high-field behavior of the device. Specifically, back-gated graphene transistors with tapered channel widths are simulated and compared to experimental data. Experimental results are fitted with a comprehensive transport model, extracting the mobility, contact resistance, conductance, and transconductance parameters. The self-consistent model includes the thermopower of graphene, which are included here within a transistor device for the first time.unpublishednot peer reviewedU of I OnlyUndergraduate senior thesis not recommended for open acces

On-Line Monitoring the Growth of E. coli or HeLa Cells Using an Annular Microelectrode Piezoelectric Biosensor

Biological information is obtained from the interaction between the series detection electrode and the organism or the physical field of biological cultures in the non-mass responsive piezoelectric biosensor. Therefore, electric parameter of the electrode will affect the biosensor signal. The electric field distribution of the microelectrode used in this study was simulated using the COMSOL Multiphysics analytical tool. This process showed that the electric field spatial distribution is affected by the width of the electrode finger or the space between the electrodes. In addition, the characteristic response of the piezoelectric sensor constructed serially with an annular microelectrode was tested and applied for the continuous detection of Escherichia coli culture or HeLa cell culture. Results indicated that the piezoelectric biosensor with an annular microelectrode meets the requirements for the real-time detection of E. coli or HeLa cells in culture. Moreover, this kind of piezoelectric biosensor is more sensitive than the sensor with an interdigital microelectrode. Thus, the piezoelectric biosensor acts as an effective analysis tool for acquiring online cell or microbial culture information