Learn More
In normal men, the majority of GH secretion occurs in a single large postsleep onset pulse that is suppressed during total sleep deprivation. We examined the impact of semichronic partial sleep loss, a highly prevalent condition, on the 24-h growth hormone profile. Eleven young men were studied after six nights of restricted bedtimes (0100-0500) and after 7(More)
This paper describes the fabrication and the performance of microfluidic paper-based electrochemical sensing devices (we call the microfluidic paper-based electrochemical devices, microPEDs). The microPEDs comprise paper-based microfluidic channels patterned by photolithography or wax printing, and electrodes screen-printed from conducting inks (e.g.,(More)
Self-organization of nanoparticles is an efficient strategy for producing nanostructures with complex, hierarchical architectures. The past decade has witnessed great progress in nanoparticle self-assembly, yet the quantitative prediction of the architecture of nanoparticle ensembles and of the kinetics of their formation remains a challenge. We report on(More)
The combination of simple Electrochemical Micro-Paper-based Analytical Devices (EµPADs) with commercially available glucometers allows rapid, quantitative electrochemical analysis of a number of compounds relevant to human health (e.g., glucose, cholesterol, lactate, and alcohol) in blood or urine.
This paper describes three-dimensional microfluidic paper-based analytical devices (3-D microPADs) that can be programmed (postfabrication) by the user to generate multiple patterns of flow through them. These devices are programmed by pressing single-use 'on' buttons, using a stylus or a ballpoint pen. Pressing a button closes a small space (gap) between(More)
We report the results of a comparative study of microfluidic emulsification of liquids with different viscosities. Depending on the properties of the fluids and their rates of flow, emulsification occurred in the dripping and jetting regimes. We studied the characteristic features and typical dependence of the size and of the size distribution of droplets(More)
We report the application of the "internal trigger" approach to multistep microfluidic polymerization reactions conducted in droplets, namely, polyaddition and polycondensation. We hypothesized and experimentally established that heat generated in an exothermic free radical polymerization of an acrylate monomer (Reaction 1) triggers the polycondensation of(More)
This article describes a new design for a paper-based electrochemical system for flow-injection analysis. Capillary wicking facilitates a gravity-driven flow of buffer solution continuously through paper and nitrocellulose, from a buffer reservoir at one end of the device to a sink at the other. A difference in height between the reservoir and the sink(More)
This paper demonstrates the use of aqueous multiphase systems (MuPSs) as media for rate-zonal centrifugation to separate nanoparticles of different shapes and sizes. The properties of MuPSs do not change with time or during centrifugation; this stability facilitates sample collection after separation. A three-phase system demonstrates the separation of the(More)
This paper describes the use of a nanoindenter, equipped with a diamond tip, to form patterns of indentations on planar substrates (epoxy, silicon, and SiO(2)). The process is called "Indentation Lithography" (IndL). The indentations have the form of pits and furrows, whose cross-sectional profiles are determined by the shapes of the diamond indenters, and(More)