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

Research during this reporting period, continued on ionic chromatography. Major progress has been made towards on-line on-demand generation of ultrapure chemicals by electrochemical means. The concentration of the generated material is governed electrochemically.

/pdf/novel-approaches-to-ionic-chromatography-1j5buykpbz.pdf

Novel approaches to ionic chromatography

How to make simple high-pressure connections using polymeric capillary tubing

Analyte identification in ion chromatography Electromigration governed chronoamperometric profiles

SIR: The article “A New Method of Generation of Gases a t Parts per Million Levels for Preparation of Standard Gases” (ES&T 1980 1 4 , 4 1 3 ) describes a simple method for generation of test gases a t low levels. I t should be pointed out that, for three out of the five systems described (NO2, SOz, and HzS), the solute is subject to oxidative degradation and it is unlikely that a constant concentration of the desired gas will be maintained in the effluent stream over a long period of time. This is, of course, what Figure 7 shows when NazS03 is used as a solute: the SO2 concentration decays rapidly with time. In this context, the authors consider the greater oxidizability of S032-, as opposed to HS03-, to be responsible. Yet, the legend associated with the figure states that both the NaHS03 and Na2S03 solutions were maintained a t pH 5 . If the buffer employed had had sufficient capacity to maintain a constant pH, it would have mattered little whether Na2S03 or NaHS03 was put in solution insofar as the relative distribution of S032-/HS03is concerned. The S032-/HS03ratio is uniquely governed by the final pH of the solution and not by the form of the salt used; S0a2is reportedly protonated with a rate constant of 1011 L mol-1 s-1 ( I ) . There are other problems associated with NO, generation by this technique. Nitrous acid is sufficiently stable in the vapor phase to constitute an appreciable fraction of what is being measured as NO,. In our studies with vaporand aerosol-phase nitrous acid, we encounter a very similar problem; HNOz is measured totally as NO2 by the Saltzman procedure and it decomposes to NO and NO2 in the chemiluminescence-type analyzers. The reliability of the data presented in Figure 4 is, therefore, open to question. The method is, however, attractive for situations where chemical instability, either for the solute in the solution or for the gas in the effluent stream, is not a problem. If fresh solution is pumped in with a peristaltic pump a t an adequate rate, constant solution composition and thus constant gas composition in the effluent stream can be assured. Oxidative degradation may, of course, be eliminated by using N2 instead of air.

A new method of generation of gases at parts per million levels for preparation of standard gases. Comments.

An electrodialytic device for ion chromatography, including aspects functioning as an eluent suppressor device and aspects functioning as an eluent generator device. In general, the device includes a monolithic block of ionomeric polymer material having (1) a first channel with an inlet port, an outlet port, and an active length of exposed polymer material disposed therebetween, (2) a second channel having an inlet port, an outlet port, and an active length of exposed polymer material disposed therebetween, (3) a first and second at-least-partially exposed electrodes positioned in electrical communication with the second channel, with the second electrode disposed, at least in part, across the second channel from the first electrode. A current flowing between the electrodes will drive an electrodialytic migration of ions between the active lengths, from an eluent stream in the case of a suppression device or into an eluent stream in the case of a generator device.

Purnendu K. Dasgupta

Papers

Novel approaches to ionic chromatography

How to make simple high-pressure connections using polymeric capillary tubing

Analyte identification in ion chromatography Electromigration governed chronoamperometric profiles

A new method of generation of gases at parts per million levels for preparation of standard gases. Comments.

Electrodialytic capillary suppressor for suppressed conductometric ion chromatography