C-H…N≡C Hydrogen Bonding in Cyanobenzene-Ethylenedithio-Tetrathiafulvalene Compounds

The importance of the C-H…N≡C interactions in the crystal engineering of conducting materials was recently put into evidence in a new type of two-dimensional conducting materials with composition (5-CNB-EDT-TTF)4A with...

Doped Polythiophene Chiral Electrodes as Electrochemical Biosensors

π-conducting materials such as chiral polythiophenes exhibit excellent electrochemical stability in doped and undoped states on electrode surfaces (chiral electrodes), which help tune their physical and electronic properties for a wide range of uses. To overcome the limitations of traditional surface immobilization methods, an alternative pathway for the detection of organic and bioorganic targets using chiral electrodes has been developed. Moreover, chiral electrodes have the ability to carry functionalities, which helps the immobilization and recognition of bioorganic molecules. In this review, we describe the use of polythiophenes for the design of chiral electrodes and their applications as electrochemical biosensors.

Reducing the Natural Convection Inside an Enclosure Using a Concentric Internal Open Square

This paper presents the results of a numerical simulation for the natural convection inside an enclosure that has an inner open square at its center. The inner square is open at the top and connected to the ceiling of the enclosure. The open inner square distorts the convection patterns, slows down the flow, and provides a compartment to confine the fluid at the core of the enclosure. Ultimately, this lowers the local Nusselt number, Nu, along the hot wall, and reduces the heat flux through the enclosure. The analysis shows the effects of changing the dimensions of the inner square on the heat flux through the enclosure for a range of Ryleigh numbers from 103 to 106. Short-sided inner squares work as flow deflectors while long-sided inner squares provide compartments to accommodate new flow circulation at the core of the enclosure. The inner square is most effective when the length of its sides equals the width of the stagnant core inside the empty enclosure at the same Ryleigh number, and the heat flux at this condition is the lowest. Inner squares made of thermally conducting materials can reduce the heat flux through the enclosure by 70%, while adiabatic inner squares can reduce the heat flux by 90%. Inner squares reduce the external heat load on buildings when fitted inside the holes of hollow bricks used in building facades. The external heat flux can be lowered by 30%-55% depending on the square material and outer side temperature.

Induction Heating for Variably Sized Ferrous and Non-Ferrous Materials through Load Modulation

Induction heating (IH) is a process of heating the electrically conducting materials especially ferromagnetic materials with the help of electromagnetic induction through generating heat in an object by eddy currents. A well-entrenched way of IH is to design a heating system pertaining to the usage of ferromagnetic materials such as stainless steel, iron, etc., which restricts the end user’s choice of using utensils made of ferromagnetic only. This research article proposes a new scheme of induction heating that is equally effective for heating ferromagnetic and non-ferromagnetic materials such as aluminium and copper. This is achieved by having a competent IH system that embodies a series resonant inverter and controller where a competent flexible load modulation (FLM) is deployed. FLM facilitates change in operating frequency in accordance with the type of material chosen for heating. The recent attempts by researchers on all metal IH have not addressed much on the variable shapes and sizes of the material, whereas this research attempts to address that issue as well. The proposed induction heating system is verified for a 2 kW system and is compatible with both industrial and domestic applications.

Thermodynamics of Organic Electrochemical Transistors

Bioelectronics which bridge the gap between conventional electronics and biological systems are actively researched due to their fascinating perspectives in healthcare and other fields. A key element of future bioelectronics is the organic electrochemical transistor (OECT) that, by employing a mixed ion-electron conducting materials, can perform switching tasks in electrolytic environments and serve as sensoric or actoric element. OECTs differ substantially from their inorganic field-effect counterparts, mainly due to their electrochemical, rather than electrostatic, gate operation principle. However, the working mechanism of OECTs is modeled as the one of the field-effect transistor: this approach not only fails to give quantitative agreement with experimental observation but also ignores the material properties of the channel and the chemical dynamics that stem for the operation of the device. Here, we present a new comprehensive unified model that can explain the behavior of OECTs across a broad range of materials, designs, and operation regimes. We treat the polymeric channel as a thermodynamic binary system and show that the entropy of mixing is the major driving force behind the operation of the OECT. We are able to quantify the entropic and enthalpic interactions between charged species for a variety of materials and solvents and harness this knowledge to provide guidelines for material modeling and insights for device fine-tuning for targeted applications. Finally, our thermodynamic model provides a description of the intrinsic origin of the ubiquitous hysteretic behavior of OECTs.

Anticorrosive Multi-band 5G Wireless Communication and THz Electromagnetic-Interference Shielding with Graphene Assembled Film

Since first developed, the conducting materials in wireless communication and electromagnetic interference (EMI) shielding devices have been primarily made of metal-based structures. Here, we present a highly conductive and corrosion-resistant graphene assembled film (GAF) that can be used to fabricate multi-band 5G wireless communication electronics and EMI protection at frequencies ranging from tens of MHz to THz to demonstrate its potential in metal replacement in practical electronics. The GAF based antennas (dipole antenna, ultra-wideband antenna and 5G wireless communication antenna array) are comparable with metal-based antennas in terms of performance and device complexity. The EMI shielding effectiveness of GAF can reach up to 127 dB in the frequency range of 2.6 GHz - 0.32 THz, and a maximum shielding effectiveness per unit thickness is of 6966 dB/mm. Furthermore, the GAF metamaterials exhibit promising frequency selection characteristics and angular stability as flexible frequency selective surfaces that can work at 3.5 GHz and 60 GHz respectively.