The manipulation of fluids in channels with dimensions of tens of micrometres--microfluidics--has emerged as a distinct new field. Microfluidics has the potential to influence subject areas from chemical synthesis and biological analysis to optics and information technology. But the field is still at an early stage of development. Even as the basic science and technological demonstrations develop, other problems must be addressed: choosing and focusing on initial applications, and developing strategies to complete the cycle of development, including commercialization. The solutions to these problems will require imagination and ingenuity.

The origins and the future of microfluidics

Nanoparticles containing magnetic materials, such as magnetite (Fe3O4), are particularly useful for imaging and separation techniques. As these nanoparticles are generally considered to be biologically and chemically inert, they are typically coated with metal catalysts, antibodies or enzymes to increase their functionality as separation agents. Here, we report that magnetite nanoparticles in fact possess an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, which are widely used to oxidize organic substrates in the treatment of wastewater or as detection tools. Based on this finding, we have developed a novel immunoassay in which antibody-modified magnetite nanoparticles provide three functions: capture, separation and detection. The stability, ease of production and versatility of these nanoparticles makes them a powerful tool for a wide range of potential applications in medicine, biotechnology and environmental chemistry.

Intrinsic peroxidase-like activity of ferromagnetic nanoparticles

http://lovely-physics.persiangig.com/document/DLLME.pdf

Determination of organic compounds in water using dispersive liquid-liquid microextraction

For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of “the dose makes the poison,” because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from...

/pdf/hormones-and-endocrine-disrupting-chemicals-low-dose-effects-2vn32zoqc8.pdf

Hormones and endocrine-disrupting chemicals: Low-dose effects and nonmonotonic dose responses

Background: Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2...

https://www.thyca.org/download/document/486/PregnancyandPostpartum.pdf

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum

A new continuous soluble particle collector (PC) that does not use steam is described. Preceded by a denuder and interfaced with an ion chromatograph, this compact collector (3 in. o.d., ∼5 in. total height) permits collection and continuous extraction of soluble components in atmospheric particulate matter. The PC is mounted atop a parallel plate wetted denuder for removal of soluble gases. The soluble gas denuded air enters the PC through an inlet. One version of the PC contained an integral cyclone-like inlet. For this device, penetration of particles as a function of size was characterized. In the simpler design, the sampled air enters the PC through a nozzle, and deionized water flows through a capillary tube placed close to the exit side of the nozzle by Venturi action or is forcibly pumped. Some growth of the aerosol occurs in the highly humid mist-chamber environment, but the dominant aerosol capture mechanism involves capture by the water film that forms on the hydrophobic PTFE membrane filter th...

A continuous analyzer for soluble anionic constituents and ammonium in atmospheric particulate matter.

La longueur de parcours effective d'une cellule a trajet multiple varie avec l'absorbance de la solution et est plus grande pour les solutions de faible absorbance

Multipath cells for extending dynamic range of optical absorbance measurements

We describe a membrane-based collection/analysis system that differentially monitors H2S and CH3SH, and to which a conductometric SO2 analyzer using the same collector was coupled. A diffusion scrubber (DS) comprised of a Nafion tube collects H2S selectively while a porous polytetrafluoroethylene (pPTFE) DS collects both H2S and CH3SH. Both gases are measured via their ability to react with fluorescein mercuric acetate (FMA) which results in decreased fluorescence. The limited dynamic range of a negative signal procedure was overcome by using dual DS units comprised of short and long scrubbers, placed serially in the liquid flow line. Different DS designs and membrane materials were investigated. H2S, CH3SH, and SO2 from a biogenic point source were continuously measured, and the H2S/CH3SH data compared well with a standard procedure involving Tedlar bag collection, preconcentration and thermal desorption from a Tenax trap, and measurement by gas chromatography/flame photometric detection. Walkaround portability of the instrument and very large dynamic range measurement of H2S and SO2 were demonstrated around the Mt. Aso volcano.

Field instrument for simultaneous large dynamic range measurement of atmospheric hydrogen sulfide, methanethiol, and sulfur dioxide.

A diffusion scrubber for the collection of atmospheric gases

Small lengths of narrow-bore tubular membranes can be interposed in the separation capillary in capillary electrophoretic separation systems. These membrane segments can be used as sampling interfaces; a jacket is built outside the membrane, and the sample is introduced by diffusion/permeation through the membrane. Various examples are shown; the determination of gaseous samples through a porous membrane, the determination of ionizable/nonionic solutes by permeation through a silicone rubber membrane, and the separation of low MW constituents in blood plasma by transport through a dialysis membrane. In the first two cases, significant preconcentration is possible, thus permitting attractive detection limits. 23 refs., 10 figs., 2 tabs.

Purnendu K. Dasgupta

Papers

A continuous analyzer for soluble anionic constituents and ammonium in atmospheric particulate matter.

Multipath cells for extending dynamic range of optical absorbance measurements

Field instrument for simultaneous large dynamic range measurement of atmospheric hydrogen sulfide, methanethiol, and sulfur dioxide.

A diffusion scrubber for the collection of atmospheric gases

Membrane interfaces for sample introduction in capillary zone electrophoresis