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

Kuntz, R.; Lonneman, W. A.; Namie, G.; Hull, L. A. Anal. Let t . 1980, 13, 1409-1415. Fed. Regist. 1979, 44, 233. Cares, J. W. Am. Ind. Hyg. Assoc. J. 1968, 29, 405-410. Pitts, J. N., Jr.; Sanhueza, E.; Atkinson, R.; Carter, W. P. L.; Winer, A. M.; Harris, G. W.; Plum, C. W. Int. J. Chem. Kinet. 1984,16, 919-939. Shepson, P. B.; Edney, E. 0.; Corse, E. W. J. Phys. Chem. 1984,88,4122-4126. Killus, J. P.; Whitten, G. Z. Atmos. Environ. 1982, 16, 1973-1988. Leone, J. A.; Seinfeld, J. H. Int. J . Chem. Kinet. 1984,16, 159-193. Haworth, S.; Lawlor, T.; Mortelmans, K.; Speck, W.; Zeiger, E. Environ. Mutagen. 1983, Suppl. 1 , 3-142. Environ Health Perspect. 1982, 43, 139-168. Kleindienst, T. E.; Shepson, P. B.; Edney, E. 0.; Claxton, L. D., submitted for publication in Mutat. Res.

Thermodynamics of the hydrogen peroxide-water system

Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial

A diffusion scrubber based automated instrument measures HONO utilizing ion chromatography and UV detection with time resolutions of 7-15 min and a detection limit of ca. 20 pptv. The thermodynamic equilibrium of NH{sub 3}(g) and HONO(g) over NH{sub 4}NO{sub 2}(s) can be described by ln (p{sub HONO}, atm) = {minus}8,018 {plus minus} 84/T + 16.81 {plus minus} 0.30 and provides a convenient and reliable source for HONO(g) free from major contamination with NO{sub x}. Ambient measurement data for Lubbock, TX, are presented. Persistent daytime concentrations of HONO in the 100-500 pptv range, weekday morning peak concentrations up to 1 ppbv following peak traffic hours, and typical nighttime peak concentrations between 1 and 2 ppbv are observed.

Measurement of ambient nitrous acid and a reliable calibration source for gaseous nitrous acid

Apparatus suitable for generating a high purity, aqueous product stream including one or more selected ionic species and using it as a chromatography eluent, comprises eluent generating means defining a source channel and a product channel, and comprises a permselective ion exchange membrane partitioning said source channel and product channel, said ion exchange membrane including exchangeable ions of the same charge as said selected ionic species and allowing transmembrane passage to ions of the same charge as said exchangeable ions and being resistant to transmembrane passage of ions of the opposite charge, means for applying an electrical potential between said source channel and product channel, chromatographic separating means, conduit means for directing aqueous product stream from said product channel to said chromatographic separation means, and means for supplying a liquid sample to said chromatographic separating means.

Method and apparatus for generating a high purity chromatography eluent

We present a new fully automated instrument for the measurement of acid gases and soluble anionic constituents of atmospheric particulate matter. The instrument operates in two independent parallel channels. In one channel, a wet denuder collects soluble acid gases; these are analyzed by anion chromatography (IC). In a second channel, a cyclone removes large particles and the aerosol stream is then processed by another wet denuder to remove potentially interfering gases. The particles are then collected by one of two glass fiber filters which are alternately sampled, washed, and dried. The washings are preconcentrated and analyzed by IC. Detection limits of low to subnanogram per cubic meter concentrations of most gaseous and particulate constituents can be readily attained. The instrument has been extensively field-tested; some field data are presented. Results of attempts to decipher the total anionic constitution of urban ambient aerosol by IC-MS analysis are also presented.

Field Measurement of Acid Gases and Soluble Anions in Atmospheric Particulate Matter Using a Parallel Plate Wet Denuder and an Alternating Filter-Based Automated Analysis System

Purnendu K. Dasgupta

Papers

Thermodynamics of the hydrogen peroxide-water system

Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial

Measurement of ambient nitrous acid and a reliable calibration source for gaseous nitrous acid

Method and apparatus for generating a high purity chromatography eluent

Field Measurement of Acid Gases and Soluble Anions in Atmospheric Particulate Matter Using a Parallel Plate Wet Denuder and an Alternating Filter-Based Automated Analysis System