Energy scavenging for mobile and wireless electronics

Energy harvesting has grown from long-established concepts into devices for powering ubiquitously deployed sensor networks and mobile electronics. Systems can scavenge power from human activity or derive limited energy from ambient heat, light, radio, or vibrations. Ongoing power management developments enable battery-powered electronics to live longer. Such advances include dynamic optimization of voltage and clock rate, hybrid analog-digital designs, and clever wake-up procedures that keep the electronics mostly inactive. Exploiting renewable energy resources in the device's environment, however, offers a power source limited by the device's physical survival rather than an adjunct energy store. Energy harvesting's true legacy dates to the water wheel and windmill, and credible approaches that scavenge energy from waste heat or vibration have been around for many decades. Nonetheless, the field has encountered renewed interest as low-power electronics, wireless standards, and miniaturization conspire to populate the world with sensor networks and mobile devices. This article presents a whirlwind survey through energy harvesting, spanning historic and current developments.     

Bovine Brain Diacylglycerol Lipase: Substrate Specificity and Activation by Cyclic AMP-dependent Protein Kinase

Diacylglycerol lipase (EC 3.1.1.3) was purified from bovine brain microsomes using multiple column chromatographic techniques. The purified enzyme migrates as a single band on SDS-PAGE and has an apparent molecular weight of 27 kDa. Substrate specificity experiments using mixed molecular species of 1,2-diacyl-sn-glycerols indicate that low concentrations of Ca²⁺ and Mg²⁺ have no direct effect on enzymic activity and 1,2-diacyl-sn-glycerols are the preferred substrate over 1,3-diacyl-sn-glycerols. The enzyme hydrolyzes stearate in preference to palmitate from the sn-1 position of 1,2-diacyl-sn-glycerols. 1-O-Alkyl-2-acyl-sn-glycerols are not a substrate for the purified enzyme. The native enzyme had a V _max value of 616 nmol/min mg protein. Phosphorylation by cAMP-dependent protein kinase resulted in a threefold increase in catalytic throughput (V _max = 1,900 nmol/min mg protein). The substrate specificity and catalytic properties of the bovine brain diacylglycerol lipase suggest that diacylglycerol lipase may regulate protein kinase C activity and 2-arachidonoyl-sn-glycerol levels by rapidly altering the intracellular concentration of diacylglycerols.     

Toward high‐efficiency dye‐sensitized solar cells with a photoanode fabricated via a simple water‐based formulation

An aqueous formulation containing commercially available P25 nanoparticles and a water‐soluble precursor—titanium (IV) bis(ammonium lactato)dihydroxide (TALH) has been developed and optimized for fabricating photoanodes in dye‐sensitized solar cells. An optimal formulation achieved a power conversion efficiency of 9.2%. Solar cell performance is significantly influenced by precursor concentration impacting the porosity and electron transport of the thin film. The use of TALH during processing is shown to enhance the electron transport in the resulting titanium dioxide nanoparticle network using transient decay measurements. Bridging between neighboring nanoparticles is confirmed using transmission electron microscopy explaining the enhanced electron transport. The developed formulation has several advantages, as it is water‐based, composed of inexpensive, non‐hazardous components, is easy to make, and does not require special handling. The formulation has great potential for industrial applications, in particular for DSC manufacturing using roll‐to‐roll technology. Copyright © 2014 John Wiley & Sons, Ltd.     

Wearable computers: no longer science fiction

By using devices carried on the body, wearable computers allow the exploration of the principles of pervasive computing immediately instead of waiting for the deployment of the ubiquitous infrastructure often associated with the field. However, wearable computers are often misunderstood, both in their research and application. I've been wearing a computer as part of my daily life since 1993, and in this article, I explore the attributes that make wearable computers a unique approach to ubiquitous computing and discuss current topics in the wearable computing field.     

Removing paraffin‐based wax coatings from old corrugated containers using supercritical carbon dioxide

Supercritical carbon dioxide (SC‐CO₂) extractions of paraffin‐based wax coatings from saturated and curtain‐coated old corrugated containers (OCC) are reported. Extractions were performed in a 500‐mL reactor (300 bar, 100°C, 50 g CO₂/min and 1 h). Wax removal efficiencies of 98 and 70% for saturated and curtain‐coated OCC, respectively, were obtained. Under similar conditions, extractions in the presence of water resulted in an extraction efficiency of 99% for saturated OCC. Decreasing the operating pressure to 200 bar decreased the extraction efficiency to approximately 50%. Gas chromatography (GC) of the wax coatings on OCC, before and after extraction with SC‐CO₂, showed a slight shift in the molecular weight distribution of the paraffin wax (after SC‐CO₂ extraction) toward higher molecular weights for both saturating wax and curtain‐coating wax. There was no evidence of chemical degradation or modification of the paraffin wax coatings by SC‐CO₂. The packing density, packing arrangement, and dimensions of the curtain‐coated OCC in the extraction apparatus affected the extraction efficiency. Loose packing compared to tight packing, 1 × 1 cm squares versus 1 × 20 cm strips, had higher extraction efficiencies; a random packing arrangement was better than packing with the fluting material in the direction of SC‐CO₂ flow. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2699–2704, 2002     

A Dual-Synchrony Chaotic Communication Scheme

We demonstrate here a new dual receiver synchronization scheme that works because we are able to store samples over an entire bit period and then perform an intelligent comparison by methods we introduce. We discuss advantages for message camouflage of transmissions near the noise floor. Our results show better bit error probability performance in comparison to previously published methods. This represents a significantly different and promising new way to use chaotic transmitters to advantageously transmit designed signals.     

Pervasive Computing and Autism: Assisting Caregivers of Children with Special Needs

Pervasive computing technologies can support children with autism and their caregivers. Work continues on systems that aid record collection and analysis, decision making, communication, and assessment of children's internal states     

Sport psychology training within a clinical psychology program and a department of intercollegiate athletics.

Many applicants to clinical and counseling psychology programs are interested in receiving the training needed to practice competently in the professional specialty area of sport psychology. In this article, the authors describe a collaborative training and service relationship between an APA-accredited clinical psychology program and an intercollegiate athletics department. Sport Psychology Services provides performance enhancement, program evaluation, and mental health services to the athletic department. In return, graduate students receive applied training, financial support, and opportunities to conduct research. The authors present program evaluation data and offer practical guidelines to graduate programs wishing to establish similar training opportunities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)