Porosity-Engineered CNT-MoS2 Hybrid Nanostructures for Bipolar Supercapacitor Applications

Bipolar supercapacitors that can store many fold higher capacitance in negative voltage compared to positive voltage are of great importance if they can be engineered for practical applications. The electrode material encompassing high surface area, better electrochemical stability, high conductivity, moderate distribution of pore size, and their interaction with suitable electrolytes is imperative to enable bipolar supercapacitor performance. Apropos of the aforementioned aspects, the intent of this work is to ascertain the effect of ionic properties of different electrolytes on the electrochemical properties and performance of a porous CNT-MoS₂ hybrid microstructure toward bipolar supercapacitor applications. The electrochemical assessment reveals that the CNT-MoS₂ hybrid electrode exhibited a two- to threefold higher areal capacitance value of 122.3 mF cm^-2 at 100 μA cm^-2 in 1 M aqueous Na₂SO₄ and 42.13 mF cm^-2 at 0.30 mA cm^-2 in PVA-Na₂SO₄ gel electrolyte in the negative potential window in comparison to the positive potential window. The CNT-MoS₂ hybrid demonstrates a splendid Coulombic efficiency of ∼102.5% and outstanding stability with capacitance retention showing a change from 100% to ∼180% over 7000 repeated charging-discharging cycles.

Monitoring Body Fluids in Textiles: Combining Impedance and Thermal Principles in a Printed, Wearable, and Washable Sensor

This work explores the feasibility of coupling two different techniques, the impedance and the transient plane source (TPS) principle, to quantify the moisture content and its compositional parameters simultaneously. The sensor is realized directly on textiles with the use of printing and coating technology. Impedance measurements use the fluid's electrical properties, while the TPS measurements are based on the thermal effusivity of the liquid. Impedance and TPS measurements show equal competency in measuring the fluid volume with a lowest measurable quantity of 0.5 μL, enabling ultralow volume passive measurements for sweat analysis. Both sensor principles were tested by monitoring the drying of a wet cloth and the measurements show perfect repeatability and accuracy. Nevertheless, when the biofluid property changes, the TPS sensor does not reflect this information on its readings, whereas, on the other hand, impedance can provide information on compositional changes. However, since the volume of the fluid changes simultaneously, one cannot differentiate between a volume change and a compositional change from impedance measurements alone. Therefore, we show in this work that we can apply impedance to measure the compositional properties; meanwhile, the TPS measurements accurately carry out volume measurements irrespective of the interferences from its compositional variations. To prove this, both of these techniques are applied for the quantification and composition monitoring of sweat, showing the capability to measure moisture content and compositional parameters simultaneously. TPS measurements can also be an indicator of the local temperature of the medium confined by the sensor, and it does not influence the fluid parameters. Compiling both impedance and thermal sensors in a single platform triggers smart wearable prospects of metering the liquid volume and simultaneously analyzing other compositional changes and body temperature. Finally, the repeatability and stability of the sensor readings and the washability of the device are tested. This device could be a potential sensing tool in real-life applications, such as wound monitoring and sweat analysis, and could be a promising addition toward future smart wearable sensors.

Understanding the Morpho-Anatomical, Physiological, and Functional Response of Sweet Basil to Isosmotic Nitrate to Chloride Ratios

Sweet basil (Ocimum basilicum L.) is a leafy green with a short-production cycle that is emerging as a model species among aromatic plants. Modulating the mineral composition of the nutrient solution has proved to be a valuable tool to uncover the mechanisms and responses that higher plants adopt in relation to the availability of mineral nutrients. The aim of this work was to examine the effects on basil of four isosmotic nutrient solutions with different nitrate to chloride ratios. These two anions share uptake and transport mechanisms in plants and are often considered antagonist. To this goal, we analyzed morpho-anatomical and physiological parameters as well as quality-related traits, such as the antioxidant capacity, the leaf color, the mineral composition, and the aromatic profile in relation to the nutrient ratios. Moreover, using a full factorial design, we analyzed leaves in two consecutive harvests. The data indicated a broad, multifaceted plant response to the different nutritional ratios, with almost all the recorded parameters involved. Overall, the effects on basil can be explained by considering an interdependent combination of the nitrate and chloride roles in plant nutrition and physiology. Our work revealed the extent of the modification that can be achieved in basil through the modification of the nutrient solution. It also provided indications for more nutrient efficient growing conditions, because a moderate increase in chloride limits the expected negative impact of a sub-optimal nitrate fertilization.

Ion Concentration Effect on Nanoscale Electrospray Modes

The phenomena and mechanism of electrospray modes in nanoscale are investigated from experiments and molecular dynamics simulations. It is found that the ionic concentration plays a crucial role in determining the dripping or the jetting modes in a nanoscale electrospray system. Molecular dynamics simulations uncover that the two modes are caused by the competition between the electric field stress and surface tension, which is similar to the mechanism in a macroscale electrospray system. However, in a nanoscale electrospray system, the two competing forces of the electric field stress and surface tension are more sensitive to the ion distributions than that in a macroscale electrospray system, in which the applied voltage and pressure dominate. With the decrease of the nozzle diameter to nanoscale, the ions not only affect the local electric field stress, but also destroy the hydrogen bonds among water molecules, which lead to that the ion concentration becomes a dominant factor in determining the electrospray modes in nanoscale. The discovery provides a novel method to control nanoscale electrospray modes, which may find potential applications for mass spectrometry, film deposition, and electrohydrodynamic printing.