The Environmental Protection Agency (EPA) provides access to information on a variety of topics related to the environment and strives to inform citizens of health risks. The EPA also has an extensive library network that consists of 26 libraries throughout the United States, which provide access to a plethora of information to EPA employees, scientists, and researchers. The EPA implemented a reorganization project to digitize their materials so they would be more accessible to a wider range of users, but this plan was drastically accelerated when the EPA was threatened with a budget cut. It chose to close and reduce the hours and services of some of their libraries. As a result, the agency was accused of denying users the “right to know” by making information unavailable, not providing an adequate strategic plan, and discarding vital materials. This case study explores the background of the digitization project, the practices implemented, and the critiques of the project.

/pdf/the-environmental-protection-agency-3gx4opzrjm.pdf

The Environmental Protection Agency

Heavy metal ions are of great concern, not only among the scientific community, especially chemists, biologists, and environmentalists, but increasingly among the general population, who are aware of the some of the disadvantages associated with them. In spite of the fact that some heavy metal ions play important roles in living systems, they are very toxic and hence capable of causing serious environmental and health problems.1-6 Some heavy metal ions, such as Fe(III), Zn(II), Cu(II), Co(II), Mn(II), and Mo(VI), are essential for the maintenance of human metabolism. However, high concentrations of these ions can lead to many adverse health effects.1,2,7-20 It is also a fact that others such as Hg(II), Cd(II), Pb(II), and As(III) are among the most toxic ions known that lack any vital or beneficial effects. Accumulation of these over time in the bodies of humans and animals can lead to serious debilitating illnesses.2,21-30 Therefore, the development of increasingly selective and sensitive methods for the determination of heavy metal ions is currently receiving considerable attention.7,23,31-36 Several methods, including atomic absorption spectroscopy, inductively coupled plasma atomic emission spectrometry, electrochemical sensoring, and the use of piezoelectric quartz crystals make it possible to detect low limits.37-40 However, these methods require expensive equipment and involve time-consuming and laborious procedures that can be carried out only by trained professionals. Alternatively, analytical techniques based on fluorescence detection are very popular because fluorescence measurements are usually very sensitive (parts per billion/trillion), easy to perform, and inexpensive.23,37,41-45 Furthermore, the photophysical properties of a fluorophore can be easily tuned using a range of routes: charge transfer, electron transfer, energy transfer, the influence of the heavy metal ions, and the destabilization of nonemissive n-π* excited states.5 Consequently, a large number of papers involving fluorescent chemosensors (see definition in section 2) have been published. In general to date, fluorescent chemosensors for anions and cations have proven popular, but those for many heavy metal ions such as Hg(II), Pb(II), Cu(II), Fe(III), and Ag(I) present challenges because these ions often act as fluorescence quenchers. Cu(II) is a typical ion that causes the chemosensor to decrease fluorescent emissions due to quenching of the fluorescence by mechanisms inherent to the paramagnetic species.46-48 Such decreased emissions are impractical for analytical purposes because of their low signal outputs upon complexation. In addition, temporal separation of spectrally similar complexes by time-resolved fluorimetry is subsequently prevented.49 Compared to the relatively well-developed fluorescent chemosensors, fluorescent chemodosimeters (see definition in section 2) have recently emerged as a research area of * Corresponding author. E-mail: jongskim@korea.ac.kr. † Hue University. ‡ Korea University. Duong Tuan Quang was born in 1970 in Thanhhoa, Vietnam, and graduated from Hue University in 1992, where he obtained his M.S. degree two years later and began his career as a lecturer in Chemistry soon afterwards. He received his Ph.D. degree in 2003 from Institute of Chemistry, Vietnamese Academy of Science and Technology. In 2006, he worked as a postdoctoral fellow in Professor Jong Seung Kim’s laboratory, Dankook University, Seoul, Korea. He was promoted as an associate professor in 2009 and went to Korea University as a research professor in 2010. His main task involved the development of chromogenic and fluorogenic molecular sensors to detect specific cations and anions. Chem. Rev. 2010, 110, 6280–6301 6280

Fluoro- and Chromogenic Chemodosimeters for Heavy Metal Ion Detection in Solution and Biospecimens

Since the late 1980s there have been spectacular developments in micromechanical or microelectro-mechanical (MEMS) systems which have enabled the exploration of transduction modes that involve mechanical energy and are based primarily on mechanical phenomena. As a result an innovative family of chemical and biological sensors has emerged. In this article, we discuss sensors with transducers in a form of cantilevers. While MEMS represents a diverse family of designs, devices with simple cantilever configurations are especially attractive as transducers for chemical and biological sensors. The review deals with four important aspects of cantilever transducers: (i) operation principles and models; (ii) microfabrication; (iii) figures of merit; and (iv) applications of cantilever sensors. We also provide a brief analysis of historical predecessors of the modern cantilever sensors.

Cantilever transducers as a platform for chemical and biological sensors

Calixarene-derived fluorescent probes.

Diagnosis and monitoring of complex diseases such as cancer require quantitative detection of multiple proteins. Recent work has shown that when specific biomolecular binding occurs on one surface of a microcantilever beam, intermolecular nanomechanics bend the cantilever, which can be optically detected. Although this label-free technique readily lends itself to formation of microcantilever arrays, what has remained unclear is the technologically critical issue of whether it is sufficiently specific and sensitive to detect disease-related proteins at clinically relevant conditions and concentrations. As an example, we report here that microcantilevers of different geometries have been used to detect two forms of prostate-specific antigen (PSA) over a wide range of concentrations from 0.2 ng/ml to 60 µg/ml in a background of human serum albumin (HSA) and human plasminogen (HP) at 1 mg/ml, making this a clinically relevant diagnostic technique for prostate cancer. Because cantilever motion originates from the free-energy change induced by specific biomolecular binding, this technique may offer a common platform for high-throughput label-free analysis of protein‐protein binding, DNA hybridization, and DNA‐protein interactions, as well as drug discovery. It is becoming increasingly evident that high-throughput identification and quantitation of a large number of biological molecules is important for generating a molecular profile that is critical in diagnosis, monitoring, and prognostic evaluation of complex diseases such as cancer

Bioassay of prostate-specific antigen (PSA) using microcantilevers.

Polycyclic aromatic hydrocarbons (PAH),t also known as polynuclear aromatic hydrocarbons or polyarenes, constitute a large class of organic compounds. They are formed and released into the environment through natural and man-made sources. Natural sources include volcanoes and forest fire, while the man-made sources come from wood burning, automobile exhaust, industrial power generators, incinerators, production of coal tar, coke, asphalt and petroleum, incomplete combustion of coal, oil, gas, garbage, tobacco and charbroiled meat. Polycyclic aromatic heterocyclic analogs containing one or more nitrogen, oxygen or sulfur atoms are also present in substantial quantities in coal tar and petroleum residues produced during the refining process. In the atmosphere, they are principally generated from the combustion of fossil fuels, wood or forest burning, refuse burning and coal tar. Although anthropogenic sources account for the major portion of atmospheric PAH pollution (l), vehicle emissions are believed to be responsible for 35% of the total PAH emission in highly populated and industrialized urban areas of the United States (2). Deposition of PAH in surface and ground waters can take place from a variety of sources such as airborne PAH, municipal wastewater discharge, effluents from wood treatment plants and other industries, oil spills and petroleum pressing. Accumulation of PAH in soils is believed to result from atmospheric deposition after long-range transport. The concentration of PAH found in soil around urban and industrialized areas are sometimes up to two orders of magnitude higher than those in less-developed areas (derived from forest fires and airborne pollution). Once released into the environment, PAH can partition between air, water, soil or sediments. An extensive body of work on this subject has appeared in the literature in recent years. Representative examples include partitioning of PAH between the gas and suspended particle phase (3,4), aidwater

A Compilation of Physical, Spectroscopic and Photophysical Properties of Polycyclic Aromatic Hydrocarbons

Cerium oxide, CeO2, nanoparticles were prepared using reverse micellar synthesis, using cerium nitrate as a starting material, sodium hydroxide as a precipitating agent, n-octane as the oil phase, cetyl trimethyl ammonium bromide (CTAB) as the surfactant, and 1-butanol as the co-surfactant. Using x-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM), the average size of the nanoparticles obtained was found to be around 3.7 nm, and the particles had a well defined polyhedral shape. The particles also showed strong UV absorption and room temperature photoluminescence. The photoluminescence peak was sensitive to the particle concentration and showed a blue-shift upon dilution.

https://iopscience.iop.org/article/10.1088/0957-4484/16/9/089/pdf

Reverse micellar synthesis of cerium oxide nanoparticles

There have been relatively few detailed studies of PAH photochemical degradation mechanisms and products at solid/air interfaces under controlled conditions. Results from mechanistic studies on par...

Photochemical oxidation of phenanthrene sorbed on silica gel

http://www.pages.drexel.edu/~hj56/PDFfiles/2000/2000chemcomm.pdf

A novel self-assembled monolayer (SAM) coated microcantilever for low level caesium detection

Porous silica surfaces are shown to slowly catalyze the oxidation of adsorbed polycyclic aromatic hydrocarbons (PAH) to the corresponding radical cation via Lewis acid sites present on the surface. When a good electron acceptor such as methyl viologen dication (MV ++ ) is co-adsorbed on silica surface, a red-shifted structureless absorption band characteristic of a ground-state charge transfer (CT) complex formed between the PAH and MV ++ is observed. Oxygen efficiently competes with MV ++ for the trapped electrons on the active sites of silica surface causing a significant decrease in the concentration of ground-state CT complex. The rate of this electron transfer process is enhanced dramatically at the solid/liquid interface when solution of PAH in a non-polar solvent is added to dry silica containing adsorbed MV ++ . Room temperature electron paramagnetic resonance (EPR) spectra of PAHs adsorbed on silica show a broad unresolved signal ( g =2.0031–2.0045) due to PAH ⋅+ radical cation which disappears in the presence of air but can be restored upon evacuation of the sample. The EPR measurements of mixed samples containing PAH and MV ++ co-adsorbed on silica show a composite signal with hyperfine structure that may be due to presence of two paramagnetic species corresponding to MV ⋅+ and possibly PAH radical cation.

Surface catalyzed electron transfer from polycyclic aromatic hydrocarbons (PAH) to methyl viologen dication: evidence for ground-state charge transfer complex formation on silica gel

Reza Dabestani

Papers

A Compilation of Physical, Spectroscopic and Photophysical Properties of Polycyclic Aromatic Hydrocarbons

Reverse micellar synthesis of cerium oxide nanoparticles

Photochemical oxidation of phenanthrene sorbed on silica gel

A novel self-assembled monolayer (SAM) coated microcantilever for low level caesium detection

Surface catalyzed electron transfer from polycyclic aromatic hydrocarbons (PAH) to methyl viologen dication: evidence for ground-state charge transfer complex formation on silica gel