E. I. du Pont de Nemours and Company, commonly referred to as DuPont, is an American chemical company that was founded in July 1802 as a gunpowder mill by Éleuthère Irénée du Pont. In the 20th century, DuPont developed many polymers such as Vespel, neoprene, nylon, Corian, Teflon, Mylar, Kevlar, Zemdrain, M5 fiber, Nomex, Tyvek, Sorona and Lycra. DuPont developed Freon for the refrigerant industry, and later more environmentally friendly refrigerants. It developed synthetic pigments and paints including ChromaFlair.In 2014, DuPont was the world's fourth largest chemical company based on market capitalization and eighth based on revenue. Its stock price is a component of the Dow Jones Industrial Average. Wikipedia.
Warheit D.B.,DuPont Company
Nano Letters | Year: 2010
Nanotechnology is currently undergoing an impressive expansion in material science research and development of systems that have novel properties due to their small size. Most of the research efforts have been focused on applications, while the implications efforts (i.e., environmental health and safety) have lagged behind. As a consequence, the success of nanotechnology will require assurances that the products being developed are safe from an environmental, health, and safety standpoint. These concerns have led to a debate among governmental agencies and advocacy groups on whether implementation of special regulations should be required for commercialization of products containing nanomaterials. Therefore the assessments of nanomaterial-related health risks must be accurate and verifiable. A mechanism for conducting well-designed toxicology studies includes rigorous attention to nanoparticle physicochemical characterization, as well as consideration of potential routes of exposure, justification of nanoparticle doses, and inclusion of benchmark controls. Unfortunately, some results obtained from earlier studies have fostered general perceptions and fears about nanoparticle health hazards-based mainly upon simple metrics such as particle size, surface area, and particle dose. In addition, there are currently held views that results of screening in silico or in vitro cell culture assays can serve as adequate screening substitutes for identifying health hazards. Some of these " misconceptions" should be challenged or confirmed by the implementation of thorough and accurately detailed nanotoxicology studies. In this article, the author briefly discusses some of the generalized "misconceptions" regarding nanomaterial toxicity and presents alternative views on these issues. © 2010 American Chemical Society.
Zhang N.,University of Pennsylvania |
Samanta S.R.,University of Pennsylvania |
Rosen B.M.,DuPont Company |
Percec V.,University of Pennsylvania
Chemical Reviews | Year: 2014
The article discusses the mechanisms and the applications in organic synthesis, materials, supramolecular, and polymer synthesis of most organic reactions mediated by single electron transfer. Each reaction or class of reactions will be discussed by starting with the original discovery publication, followed by a summary of all or most review articles published in the field, and a discussion of the mechanism(s) and of the most important methodologic and synthetic developments since the most recent review was published. The mechanisms of most organic reactions are considered to proceed by two-electron transfer pathways, even though both biology and radical chemistry rely extensively on one-electron transfer processes. Radicals generated by homolytic cleavage at high temperature were traditionally employed in the industrial production of polymers and to a lesser extent in the synthesis of organic molecules.
Warheit D.B.,DuPont Company
Toxicology Letters | Year: 2013
Due to its multifunctional applications, titanium dioxide particles have widespread use in commerce. The particle-types function as sources of pigment color, in food products, anti-bacterial components, ultraviolet radiation scavengers, catalysts, as well as in cosmetics. Because of its inherent properties in a diverse number of products, exposures may occur via any of the major point-of-entry routes, i.e., inhalation, oral or dermal. Although the majority of TiO2 applications are known to exist in the pigment-grade form, nanoscale forms of TiO2 are also common components in several products. This brief review is designed to identify relevant toxicology and risk-related issues which inform health effects assessments on the various forms of titanium dioxide particles. While there has been an abundance of hazard data generated on titanium dioxide particulates, many of the published reports have limited informational value for assessing health effects due, in large part, to shortcomings in experimental design issues, such as: (1) inadequate material characterization of test samples; (2) questionable relevance of experimental systems employed to simulate human exposures; (3) applications of generally high doses, exclusive focus on acute toxicity endpoints, and a lack of reference benchmark control materials, to afford interpretation of measured results; and/or (4) failure to recognize fundamental differences between hazard and risk concepts. Accordingly, a number of important toxicology issues are identified and integrated herein to provide a more comprehensive assessment of the health risks of different forms of pigment-grade and nanoscale titanium dioxide particles. It is important to note that particle-types of different TiO2 compositions may have variable toxicity potencies, depending upon crystal structure, particle size, particle surface characteristics and surface coatings. In order to develop a more robust health risk evaluation of TiO2 particle exposures, this review focuses on the following issues:(1)Introduction to TiO2 particle chemistry/functionality and importance of robust material characterization of test samples;(2)Implementation of meaningful hazard studies for gauging EHS safety issues - pulmonary bioassay data and development of the Nano Risk Framework for developmental nano TiO2 compounds;(3)Epidemiological study findings on titanium dioxide workers - the most heavily-exposed populations;(4)Methodologies for setting occupational exposure limits including benchmarking or bridging comparisons; and(5)The importance of particle overload data in the lungs of rats as it relates to gauging the relevance of health effects for humans.A comprehensive evaluation of the existing animal and human health data is a necessary prerequisite for facilitating accurate assessments of human health risks to TiO2 exposures. © 2013 Elsevier Ireland Ltd.
Robinson J.G.,University of Iowa |
Gidding S.S.,DuPont Company |
Gidding S.S.,Thomas Jefferson University
Journal of the American College of Cardiology | Year: 2014
Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death in developed and developing countries. Despite decades of effort, unhealthy lifestyle habits and ASCVD risk factor levels remain high and are increasing in many population groups. A new approach to ASCVD prevention is needed. Multiple lines of evidence from animal and human studies suggest that atherosclerosis regression and normalization of vessel function can occur when low-density lipoprotein cholesterol (LDL-C) lowering occurs early in the course of atherosclerosis or when very aggressive LDL-C lowering occurs somewhat later. We propose a new paradigm focused on curing atherosclerosis early in the course of the disease. An approach that resets the vascular aging clock composed of initial regression therapy followed by periodic retreatment to suppress atherosclerosis development may be possible, with the ultimate goal of preventing subsequent ASCVD events. Proof-of-concept studies are needed to determine: 1) the optimal age and/or extent of atherosclerosis for intervention and LDL-C-lowering therapy; 2) the intensity and duration of therapy for inducing atherosclerosis regression; and 3) documenting the normalization of vascular function. Ultimately, this new paradigm will need to be evaluated in ASCVD outcomes trials. © 2014 by the American College of Cardiology Foundation. Published by Elsevier Inc.
Perry S.A.,DuPont Company
Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies | Year: 2013
We investigated the in vitro inspired dose and particle size distribution of albuterol delivered by a vibrating mesh nebulizer through the Vapotherm (Stevensville, MD) humidified high-flow nasal cannula system. Albuterol (2.5 mg/3 mL) was delivered by an Aeroneb Solo (Aerogen, Galway, Ireland) nebulizer that was connected via adaptor proximal to the nasal cannula and downstream from the Vapotherm 2000i. Albuterol was collected onto an inspiratory filter mounted to a breath simulator programmed with age-appropriate breathing patterns. Particle sizing was completed by cascade impaction. Albuterol was quantified using ultraviolet spectrometry. Measurements were made using varying flow rates through infant, pediatric, and adult nasal cannulae. Aerosol research laboratory. The inspired dose (percent of nominal dose) for each cannula size and flow rate was 2.5%, 0.8%, 0.4%, and 0.2% for the adult cannula at 5, 10, 20, and 40 L/min, respectively; 1.2%, 0.6%, 0.1%, and 0.0% for the pediatric cannula at 3, 5, 10, and 20 L/min, respectively; and 0.6%, 0.6%, and 0.5% for the infant cannula at 3, 5, and 8 L/min, respectively. Most (62-80%) of the loaded albuterol dose accumulated within the adaptor. For each cannula size, there was a significant decrease in the inspired dose with increasing flow rates, p = 0.026 (infant), p = 0.001 (pediatric), and p < 0.001(adult). The inspired dose increased with increasing cannula size for 5, 10, and 20 L/min (p = 0.007, p < 0.001, and p = 0.005, respectively). The mass median aerodynamic diameter for all trials was less than 5 μm. The amount of albuterol delivered with the Vapotherm system using this model was lower than the amount expected for a clinical response for the majority of flow rates and cannula size combinations. Further studies are needed before routine use of aerosolized albuterol through a Vapotherm high-flow system can be recommended.