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

Superheated water eluent capillary liquid chromatography

The novel concept of a nested loop valve system wherein one injection valve is inserted within the loop of another has some unique benefits. This is demonstrated for part-per-billion level differential flow injection analysis of aqueous H/sub 2/O/sub 2/ and organic peroxides. 15 references, 3 figures.

Application of a nested loop system for the flow injection analysis of trace aqueous peroxides

Automated Measurement of Atmospheric Trace Gases: Diffusion-Based Collection and Analysis

In a new approach to evaluating the oxidative stability of oils and fats, the consumption of oxygen by a sample confined in a reactor of adjustable temperature is monitored with a gas-phase flow in...

Determination of oxidative stability of oils and fats.

A new automated instrument for the near-real-time measurement of atmospheric formaldehyde is described. The chemistry involves the cyclization reaction of formaldehyde with 1,3-cyclohexanedione (CHD) In the presence of ammonium ions to form a fluorescent dihydropyridine derivative. A GaN-based light-emitting diode (LED) emitting in the near UV was used as the excitation source in a miniature flowthrough fluorescence detector based on a transversely illuminated liquid-core waveguide. The Instrument is configured to operate in a periodic autozero mode where the exhaust from the sampling pump is chemically treated to provide zero gas for automated periodic checks of the baseline. The liquid-phase portion of the system provides a S/N = 3 limit of detection (LOD) of 10-nM aqueous formaldehyde. A thermostated Nafion®-membrane-based diffusion scrubber is used to collect atmospheric formaldehyde into pure water with an absorption efficiency of ∼70%, which results in an LOD of 30 pptv HCHO. (In cases where the H 2 O 2 to HCHO ratio is very high, as in background polar atmospheres, the LOD will deteriorate markedly.) Design, performance details, and illustrative results from a 1999 field campaign (Atlanta Supersite Study) are presented. Interference from H 2 O 2 is discussed in detail.

Purnendu K. Dasgupta

Papers

Superheated water eluent capillary liquid chromatography

Application of a nested loop system for the flow injection analysis of trace aqueous peroxides

Automated Measurement of Atmospheric Trace Gases: Diffusion-Based Collection and Analysis

Determination of oxidative stability of oils and fats.

Measurement of atmospheric formaldehyde with a diffusion scrubber and light‐emitting diode–liquid‐core waveguide based fluorometry