Electrochemical impedance spectroscopy (EIS) is widely used to probe the physical and chemical processes in lithium (Li)-ion batteries (LiBs). The key parameters include state-of-charge, rate capacity or power fade, degradation and temperature dependence, which are needed to inform battery management systems as well as for quality assurance and monitoring. All-solid-state batteries using a solid-state electrolyte (SE), promise greater energy densities via a Li metal anode as well as enhanced safety, but their development is in its nascent stages and the EIS measurement, cell set-up and modelling approach can be vastly different for various SE chemistries and cell configurations. This review aims to condense the current knowledge of EIS in the context of state-of-the-art solid-state electrolytes and batteries, with a view to advancing their scale-up from the laboratory to commercial deployment. Experimental and modelling best practices are highlighted, as well as emerging impedance methods for conventional LiBs as a guide for opportunities in the solid-state.

An implantable integrated stimulator and telemetry system has been developed. The system is capable of fulfilling the stimulus and telemetry needs of advanced functional neuromuscular stimulation (FNS) applications requiring multiple channels of stimulation and multiple channels of sensor or biopotential sensing. This system provides a command control structure, an inductive radio frequency link providing power to the implant device as well as two-way transcutaneous communication, an ASIC for decoding the command and for providing functional control within the implant, and modular circuitry providing the application specific implant functions. Biocompatible hermetic packaging, lead systems, and in-line connectors suitable for long-term implantation, provide encapsulation for the circuitry and access to the electrodes and sensors used in the application. The first implant configuration realized from this modular system is targeted for clinical implementation in persons with tetraplegia at the C6 level for restoration of hand function, using wrist position as the command control source. The implant device realized has ten channels of stimulation and telemetry used to control and sense a joint angle transducer implanted in the radio-carpal joint of the wrist. A prototype device has been fabricated and is undergoing testing in an animal.

An ionic or electric wind is a bulk air movement induced by electrohydrodynamic (EHD) phenomena in a gas discharge. Because they are silent, low power, respond rapidly, and require no moving parts, ionic wind devices have been proposed for a wide range of applications, ranging from convection cooling and food drying to combustion management. The past several decades have seen the area grow tremendously leading to a number of new actuation strategies and devices that can be incorporated into various applications. In this review, we discuss the physics of ionic winds and recent developments of the past five years that have pushed the field forward, focusing on the development on bulk air-moving devices we term EHD pumps. We then highlight the ongoing challenges with transitioning ionic wind technologies to the market place, from issues that affect robustness to practical implementation, and point to areas where future research could have an impact on the field.

The membrane-associated serine hydrolase, monoacylglycerol lipase (MGL), is a wellrecognized therapeutic target that regulates endocannabinoid signaling. Crystallographic studies, while providing structural information about static MGL states, offer no direct experimental insight into the impact of MGL's membrane association upon its structure-function landscape. We report application of phospholipid bilayer nanodiscs as biomembrane models with which to evaluate the effect of a membrane system on the catalytic properties and conformational dynamics of human MGL (hMGL). Anionic and charge-neutral phospholipid bilayer nanodiscs enhanced hMGL's kinetic properties [apparent maximum velocity (V max ) and substrate affinity (K m )]. Hydrogen exchange mass spectrometry (HX MS) was used as a conformational analysis method to profile experimentally the extent of hMGL-nanodisc interaction and its impact upon hMGL structure. We provide evidence that significant regions of hMGL lid-domain helix a4 and neighboring helix a6 interact with the nanodisc phospholipid bilayer, anchoring hMGL in a more open conformation to facilitate ligand access to the enzyme's substrate-binding channel. Covalent modification of membraneassociated hMGL by the irreversible carbamate inhibitor, AM6580, shielded the active site region, but did not increase solvent exposure of the lid domain, suggesting that the inactive, carbamylated enzyme remains intact and membrane associated. Molecular dynamics simulations generated Abbreviations: 2-AG, 2-arachidonoylglycerol; AHMMCE, arachidonoyl 7-hydroxy-6-methoxy-4-methylcoumarin ester; CB1R, cannabinoid receptor 1; CB2R, cannabinoid receptor 2; FPLC, fast protein liquid chromatography; hMGL, human monoacylglyceorl lipase; HX, hydrogen exchange; K m , apparent dissociation constant; MALDI-TOF, matrix-assisted laser desorption ionizationtime of flight; MD, molecular dynamics; MGL, monoacylglycerol lipase; MS, mass spectrometry; MSP, membrane scaffold protein; MSP1D1, membrane scaffold protein 1D1; PDB, protein data bank; POPC, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine; POPG, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; V max , apparent maximum velocity Additional Supporting Information may be found in the online version of this article.Grant sponsor: National Institutes of Health; Grant numbers: DA003801 and DA009158 (to AM); Grant sponsor: National Institute on Drug Abuse; Grant numbers: GM08607 and GM101135 (to JRE); Grant sponsors: National Institute of General Medical Sciences and by a research collaboration with Waters Corporation (to JRE). Published by Wiley-Blackwell. V C 2013 The Protein Society conformational models congruent with the open, membrane-associated topology of active and inhibited, covalently-modified hMGL. Our data indicate that hMGL interaction with a phospholipid membrane bilayer induces regional changes in the enzyme's conformation that favor its recruiting lipophilic substrate/inhibitor from m...

To generate a gas discharge (plasma) in atmospheric air requires an electric field that exceeds the breakdown threshold of ∼30 kV/cm. Because of safety, size, or cost constraints, the large applied voltages required to generate such fields are often prohibitive for portable applications. In this work, piezoelectric transformers are used to amplify a low input applied voltage (<30 V) to generate breakdown in air without the need for conventional high-voltage electrical equipment. Piezoelectric transformers (PTs) use their inherent electromechanical resonance to produce a voltage amplification, such that the surface of the piezoelectric exhibits a large surface voltage that can generate corona-like discharges on its corners or on adjacent electrodes. In the proper configuration, these discharges can be used to generate a bulk air flow called an ionic wind. In this work, PT-driven discharges are characterized by measuring the discharge current and the velocity of the induced ionic wind with ionic winds generated using input voltages as low as 7 V. The characteristics of the discharge change as the input voltage increases; this modifies the resonance of the system and subsequent required operating parameters.

Monolayers of 4-tetradecaneamido-2,2,6,6-tetramethyl-1-piperidinyloxy (C 14 TEMPO) were investigated at the air/water interface. Pressure-area diagrams and Brewster angle microscopy provided evidence of supercritical state of this monolayer at temperatures as low as 2°C. The supercritical character of C 14 TEMPO Langmuir monolayers allowed the 2-D voltammetric measurements of its lateral diffusion constant, D, to be extended into a previously inaccessible region of low surface densities with mean molecular areas A ∼ 600 Å 2 /molecule. At A > 250 Å 2 /molecule, D becomes independent of the C 14 TEMPO surface concentration and depends solely on the hydrodynamic coupling of the polar headgroup to the aqueous subphase. These measurements and the supercritical state of C 14 TEMPO monolayer open a possibility to probe the viscoelastic properties of the water liquid-vapor interfacial region.

A 2D electrochemical time-of-flight (ETOF) method was developed to measure diffusion constants of lateral mobility of amphiphiles and lateral electron hopping in Langmuir monolayers at the air/water interface. Photolithographically fabricated generator-collector ETOF devices featured two parallel gold microelectrodes (7 mm in length, 40 microm wide, spaced by a 10-microm gap). In 2D ETOF measurements, such a device is touching the water surface where the generator and collector electrodes function as a collinear pair of line microelectrodes. Bulk measurements, with a generator-collector device submerged in an electrolyte solution, were carried out to calibrate the devices by relating the transit times to the known D values of Ru(NH3)6(2+) in a series of solutions of different viscosity adjusted with sucrose. A new method to define and to measure transit times in the step mode ETOF experiments was developed that requires only the pseudo-steady-state values of the collector current. Reliability of the 2D ETOF technique was established by investigating lateral diffusion of an amphiphilic tetradecane TEMPO derivative for which the D values were also measured by 2D voltammetry. Combination of 2D ETOF and 2D voltammetry allows one to independently measure diffusion coefficients and concentrations of redox species. This advantageous feature was then used to reevaluate kinetics of lateral electron hopping in Os(DPP)3(ClO4)2 (DPP, 4,7-diphenyl-1,10-phenanthroline) solid monolayers on the water surface. The true rate constant of electron self-exchange, kex = 1.0 x 10(9) M(-1) s(-1), was obtained. The fact that the latter is more than 1 order of magnitude larger than its value obtained in a homogeneous acetonitrile solution suggests that the structure and locale of the Os(DPP)3(III+/II+) monolayer system result in a larger electronic coupling and/or smaller reorganization energy.

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