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

Provided is a pretreatment device for analysis of dissolved ions, which enables the separation of dissolved ions to be analyzed from a sample solution in a short period of time and which is applicable to both a case in which the dissolved ions to be measured is a cation and a case in which the dissolved ions to be measured is an anion. A pretreatment device 10 for analysis of dissolved ions, which comprises: a sample solution flow channel 11 through which a sample solution containing dissolved ions to be measured flows; an acceptor solution flow channel 13 which is arranged adjacent to the sample solution flow channel 11 so as to intercalate a dialysis membrane 12 between the acceptor solution flow channel 13 and the sample solution flow channel 11; a pair of electrodes 14 a, 14 b which are so arranged as to intercalate the sample solution flow channel 11 and the acceptor solution flow channel 13 therebetween; and a direct current power source 5 which enables the generation of a predetermined potential difference between the electrodes 14 a, 14 b. When the pretreatment device 10 is used, it becomes possible to separate dissolved ions to be analyzed from a sample solution in a short period of time, and the device 10 is effective for a pretreatment in the analysis of an ion, such as the ion chromatography method, the ICP emission spectrometry method, the atomic absorption spectrometry method, and the mass spectrometry method.

Pretreatment device for dissolved ions analysis and dissolved ion analysis system

The mercury translation principle, wherein S(IV) reacts with Hg(l) to produce Hg(ll) and Hg(O), was utilized to measure trace levels of SO2 with a conductometric gold film sensor. One approach involved impregnated glass fiber filters containing mercurous salts. The second and more successful approach utilized a porous membrane reactor where the reaction occurs in the interstitial liquid-gas interface as the sample gas flows inside and a dilute solution of Hg2(NO3)2 flows outside the porous PTFE membrane tube. The first approach attained a LOD of 200 pptv SO2(g), however, batch to batch reproducibility of the filters was poor and the filters could not be stored more than two days. The membrane reactor method provided better translation efficiency and highly reproducible results, with an LOD of 50 pptv SO2(g). An intercomparlson of this method with an independent method relying on completely different chemistry showed good agreement for the measurement of subppbv levels of ambient SO2. Both mercury translat...

Measurement of trace levels of atmospheric sulfur dioxide with a gold film sensor

Solvent extraction in continuous flow systems with intelligent zone sampling

We describe here a simple photothermal detection scheme in a flow stream based on the temperature difference upstream and downstream of the point of illumination. We use a single, two-junction 25 μm diameter thermocouple to measure the temperature change. The baseline standard deviation in the dark is ∼0.001 °C that increases up to 0.0016 °C depending on the illumination source. We demonstrate the detection of several chromatographically separated dyes both with a 1.5 mm and a 0.1 mm i.d. detection cell, respectively, with a white LED and a solid-state laser source. With an inexpensive 660 nm, 19 mW laser as the light source, the estimated detection limit for methylene blue (MB) was 30 nM, corresponding to 120 amol in the illuminated volume. The dimerization constant of MB and the quantum efficiency of the monomer was determined.

Purnendu K. Dasgupta

Papers

Pretreatment device for dissolved ions analysis and dissolved ion analysis system

Measurement of trace levels of atmospheric sulfur dioxide with a gold film sensor

Solvent extraction in continuous flow systems with intelligent zone sampling

Direct Photothermal Measurement of Optical Absorption in a Flow System.

Methode und Gerät zum Nachweis von chemischen Substanzen mittels Lichtleitern mit flüssigem Kern