Interfacing organic electrochemical transistors (OECTs) with biological systems holds considerable promise for building-sensitive biosensors and diagnostic tools. We present a simple model that describes the performance of biosensors in which an OECT is integrated with a biological barrier layer. Using experimentally derived parameters we explore the limits of sensitivity and find that it is dependent on the resistance of the barrier layer. This work provides guidelines on how to optimize biosensors in which OECTs transduce changes in the impedance of biological layers, including lipid bilayer membranes and confluent cell layers.

In this article, monolithic porous silsesquioxane materials, which are derived by sol–gel from trialkoxysilanes with substituent groups such as trimethoxysilane (HTMS), methyltrimethoxysilane (MTMS), and vinyltrimethoxysilane (VTMS), are reviewed with a special emphasis on our recent works. Careful controls over fundamental synthetic parameters such as pH, amounts of water and solvent, and kind of solvent and additives play a crucial role in the formation of monolithic gels based on random polysiloxane networks. Crystalline/amorphous precipitation is otherwise observed when the formation of isolated species including polyhedral oligomeric silsesquioxanes dominates or if phase separation of the hydrophobic networks in aqueous media is not adequately controlled. In the successfully controlled system, pore size can be varied from a few tens of nanometers to a few tens of micrometers; porous materials such as transparent aerogels and hierarchically porous monoliths have been explored. In addition, unique properties derived from trialkoxysilanes such as reactivity of the pore surface and flexible mechanical properties are demonstrated. Possibilities in the silsesquioxane materials with controlled pore structures are discussed.

The solid–water interface is ubiquitous in natural and synthetic systems as the primary site for chemical reactions under near-ambient conditions. Examples include the interactions of contaminants with mineral–water interfaces in natural environments, electrochemical reactions at the electrode-electrolyte interface relevant to energy storage (e.g., ion adsorption/electrical double layer formation, ion insertion), and oxidation of structural materials (e.g., rust). Yet many of these phenomena remain largely mysterious at a mechanistic level. The x-ray reflectivity technique, using highly penetrating hard x-rays, directly probes the solid–water interfaces through in situ studies. This approach has provided new insights into the molecular-scale structures and processes that occur at these “wet” interfaces. In this article, we review recent advances in the understanding of these systems, focusing specifically on the organization of interfacial “hydration layers” and the important role of adsorbed ions at charged solid–liquid interfaces.

In this work, the electrical characterization of nanocomposites made of epoxy resins with multiwalled carbon nanotubes is presented. As the filler, two different types of multiwalled carbon nanotubes with different aspect ratios (280, 1250) and defectiveness were selected. The production procedure, the morphological characterization, the I–V DC characteristics, and the low frequency complex permittivity (in the range 100 kHz–12 MHz) of these nanocomposites are discussed. To investigate the dispersion of the solution, a study which linked the mixing time to the zeta potential was performed. The experimental results show that with the same matrix and by using the same measurement techniques, the two nanocomposites give different results and can be correlated with the characteristics of nanotubes. The dc conductivity of the nanocomposites was measured by means of a two-point probe technique. The conductivity in the frequency range 100 KHz–12 MHz was evaluated using a circular disk capacitor and measuring the impedance. The measured conductivity follows a percolation scaling law of the form σ ∝ (p − p c)t . A best fit to the measured conductivity data was obtained and the values of the exponent t compared to those in the literature.

Clay minerals are layered magnesium or aluminum silicates, which are abundant in the earth’s crust. Used since ancient times for the fabrication of bricks or terracotta, they now find application in the pharmaceutical and plastics industries. They play an essential role in oil and gas recovery, in water availability, and in preventing the dissemination of pollutants. In all of these contexts, the relevant properties of clay minerals are intimately linked to their microscopic structure, which results in a rich behavior with respect to water, solutes, and other fluids. This article provides a brief overview of the structure, dynamics, thermodynamics, and reactivity of water in clays, highlighting the role of the various types of water–mineral interfaces. Based on recent experimental and simulation studies, we discuss several features of these interfacial materials arising from their interactions with water on the molecular scale, including swelling, wetting, hydrodynamics in clay nanopores, reactivity of clay edge sites, ion exchange, and sorption.

The influence of predeformation and stress on the isothermal bainite transformation has been investigated in G55SiMoV steel via microstructure observation and kinetic analysis. It was found that the bainite transformation became faster and at the end of isothermal holding the bainite fraction increased under the applied stress condition. When the stress increased to 150 MPa, the bainite distribution became to be nonrandom in G55SiMoV steel. Different deformation conditions, in which both promotion and inhibition occurred in the same steel, were created. The promoting and inhibiting factors affected bainite transformation comprehensively. 20% deformation could promote the bainite transformation when it deformed at 900 °C, but prevent bainite transformation when it deformed at 750 °C. Increase of ferrite nucleation rate caused by distortion and dislocation, would suppress the growth of bainite carbides and make most carbides without full growth be finer and shorter.

Thin-film electrocaloric and pyroelectric sources for electrothermal energy interconversion have recently emerged as viable means for primary and auxiliary solid-state cooling and power generation. Two significant advances have facilitated this development: (1) the formation of high-quality polymeric and ceramic thin films with figures of merit that project system-level performance as a large percentage of Carnot efficiency and (2) the ability of these newer materials to support larger electric fields, thereby permitting operation at higher voltages. This makes the power electronic architectures more favorable for thermal to electric energy interconversion. Current research targets to adequately address commercial device needs including reduction of parasitic losses, increases in mechanical robustness, and the ability to form nearly freestanding elements with thicknesses in the range of 1–10 μm. This article describes the current state-of-the-art materials, thermodynamic cycles, and device losses and points toward potential lines of research that would lead to substantially better figures of merit for electrothermal energy interconversion.

Nanoparticle (NP) surface properties define how engineered nanomaterials interact with proteins. In aqueous systems, these interactions are driven by the binding of water to NPs and proteins. Understanding the true nature of this NP–water interface and its involvement in the properties of nanomaterials is a fundamental challenge in nanotechnology. Here, we review recent studies on the involvement of water molecules in the interaction of NPs with proteins. We first address the thermodynamic aspects of the NP–protein interaction and the means by which solvation shells can alter the nature of this phenomenon. We then discuss how the chemical nature of the NP surface affects the adsorption of water molecules and how this adsorption can either favor or inhibit protein–NP interactions.

Particles ranging in size from a few nanometers to tens of micrometers have a strong tendency to adsorb at interfaces between two immiscible fluids (e.g., water and oil or air). The driving force for this strong interfacial attachment is a reduction in interfacial area, and thus, interfacial energy. To design and engineer the structure and properties of materials constructed by such colloidal systems, it is imperative to understand the behavior of particles at fluid interfaces at the single-particle level and to establish the relationship between the microscopic behavior of interfacial particles and the bulk properties of particle-laden interfaces. In this article, we present background information on the behavior of particles at fluid–fluid interfaces and highlight recent advances in understanding the effects of particle shape and surface wettability on the behavior of particles at the interfaces. We also discuss recent advances in using interfacial attachment to direct the assembly of nanomaterials to create hierarchical structures with designed properties.