A strategy for assessing workplace exposures to nanomaterials.

This article describes a highly tailorable exposure assessment strategy for nanomaterials that enables effective and efficient exposure management (i.e., a strategy that can identify jobs or tasks that have clearly unacceptable exposures), while simultaneously requiring only a modest level of resources to conduct. The strategy is based on strategy general framework from AIHA® that is adapted for nanomaterials and seeks to ensure that the risks to workers handling nanomaterials are being managed properly. The strategy relies on a general framework as the basic foundation while building and elaborating on elements essential to an effective and efficient strategy to arrive at decisions based on collecting and interpreting available information. This article provides useful guidance on conducting workplace characterization; understanding exposure potential to nanomaterials; accounting methods for background aerosols; constructing SEGs; and selecting appropriate instrumentation for monitoring, providing appropriate choice of exposure limits, and describing criteria by which exposure management decisions should be made. The article is intended to be a practical guide for industrial hygienists for managing engineered nanomaterial risks in their workplaces.

Changing the dose metric for inhalation toxicity studies: short-term study in rats with engineered aerosolized amorphous silica nanoparticles.

Inhalation toxicity and exposure assessment studies for nonfibrous particulates have traditionally been conducted using particle mass measurements as the preferred dose metric (i.e., mg or microg/m(3)). However, currently there is a debate regarding the appropriate dose metric for nanoparticle exposure assessment studies in the workplace. The objectives of this study were to characterize aerosol exposures and toxicity in rats of freshly generated amorphous silica (AS) nanoparticles using particle number dose metrics (3.7 x 10(7) or 1.8 x 10(8) particles/cm(3)) for 1- or 3-day exposures. In addition, the role of particle size (d(50) = 37 or 83 nm) on pulmonary toxicity and genotoxicity endpoints was assessed at several postexposure time points. A nanoparticle reactor capable of producing, de novo synthesized, aerosolized amorphous silica nanoparticles for inhalation toxicity studies was developed for this study. SiO(2) aerosol nanoparticle synthesis occurred via thermal decomposition of tetraethylorthosilicate (TEOS). The reactor was designed to produce aerosolized nanoparticles at two different particle size ranges, namely d(50) = approximately 30 nm and d(50) = approximately 80 nm; at particle concentrations ranging from 10(7) to 10(8) particles/cm(3). AS particle aerosol concentrations were consistently generated by the reactor. One- or 3-day aerosol exposures produced no significant pulmonary inflammatory, genotoxic, or adverse lung histopathological effects in rats exposed to very high particle numbers corresponding to a range of mass concentrations (1.8 or 86 mg/m(3)). Although the present study was a short-term effort, the methodology described herein can be utilized for longer-term inhalation toxicity studies in rats such as 28-day or 90-day studies. The expansion of the concept to subchronic studies is practical, due, in part, to the consistency of the nanoparticle generation method.

Insight into the behavior of engineered aerosolized nanoparticles: a method for understanding their fate from an aerosol release in the workplace environment.

We present a method to assess the behavior of aerosol nanoparticles as a function of time and of selected aerosol chamber and environmental conditions upon exposure to polydisperse silicon dioxide (SiO2) aerosol nanoparticles (NPs). Through synthesis of SiO2 aerosol NPs, a well-controlled, stable source of aerosol NPs was used to probe aerosol behavior in an enclosed aerosol chamber. This paper describes a procedure to interface an aerosol chamber downstream of a SiO2 aerosol NP reactor that is capable of synthesizing SiO2 NPs with particle diameters from 10 to 100 nm at particle concentrations of approximately 10(4) to 10(7) particles/cm3. This paper also describes the relative impact on aerosol and aerosol chamber variables, such as chamber volume, the entering aerosol NP size distribution, and environmental parameters, such as relative humidity and ambient particle concentrations, on the observed changes in aerosol NPs over time under unmixed conditions. These findings provide insights into aerosol NP behavior under ideal, well-controlled conditions which can be further refined to include more occupationally relevant conditions that would be important for establishing guidance on suitable workplace containment and controls.

SiO2 aerosol nanoparticle reactor for occupational health and safety studies.

Important questions are emerging about potential occupational safety, toxicological, and ecotoxicological effects and occupational inhalation exposure risks to engineered aerosol nanoparticles. Although multiple avenues are available to synthesize nanoparticles, few tools are accessible to industrial hygienists and inhalation toxicologists to produce well-characterized aerosols of known aerosol size distribution and particle number concentration that are stable, simple, and robust to operate. This article describes a SiO(2) aerosol nanoparticle reactor that has been developed as a tool for the study of the safety, health, and environmental consequences of exposure to nanoparticle synthesis and processing. The SiO(2) aerosol nanoparticle reactor is capable of stable, long-term synthesis of amorphous SiO(2) aerosol nanoparticles from d(50) = 10-70 nm at particle concentrations approximately 10(4)-10(7)particles/cm(3) that does not produce halogen-containing byproducts and does not require daily monitoring of the particle size distribution. This reactor is designed to produce a well-characterized aerosol to enable subsequent testing with a continuous, stable supply of aerosol nanoparticles (i) to facilitate inhalation toxicology studies, (ii) to measure explosion characteristics of aerosol nanoparticles, (iii) to determine the barrier efficacy for respirator filtration, bag house exhaust, and personal protective garment media challenged with diverse aerosol nanoparticles, and (iv) to develop airborne monitoring technologies for verifying workplace safety protocols. This article details reactor design, synthesis parameters, and instruments available to characterize the resulting aerosol nanoparticle size distributions.

Organotemplate-Free ß Zeolites: From Zeolite Synthesis to Hierarchical Structure Creation.

Interest in the production of ß zeolites in the absence of organic structure-directing agent (OSDA) has continued to grow consistently during the past decade. During this time, numerous strategies have been proposed to manipulate the hierarchy of zeolite pore structures in order to facilitate the transport of bulky reactants and to improve the accessibility of active sites in zeolite catalysts. In this work, we describe an organotemplate-free route to produce hierarchical ß zeolites. Using OSDA-free ß as the starting zeolites, we explored the applicability of various postsynthetic approaches to create hierarchical structures with mesoporosity, including framework stabilization, dealumination, conventional desilication, and hydrothermal desilication. While framework stabilization and dealumination were not effective in generating mesoporosity, they were necessary as modification steps to determine the efficacy of hierarchical structure creation. Compared to conventional desilication, hydrothermal desilication produces larger mesopores and much better preservation of microporosity and acidity because of the occurrence of recrystallization. The cost-effective, scalable production of organotemplate-free hierarchical ß zeolites could greatly enhance the adoption of ß zeolites in oil refining and petrochemical industries, where the advantages of hierarchically structured zeolites can dramatically improve catalytic performances in formulated catalysts.

Data on dielectric strength heterogeneity associated with printing orientation in additively manufactured polymer materials.

The following data describe the dielectric performance of additively manufactured polymer materials printed in various orientations for four common additive manufacturing techniques. Data are presented for selected commercial 3D printing materials fabricated using four common 3D printing techniques: Stereolithography (SLA), Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS), and Polymer Jetting (PolyJet). Dielectric strengths are compiled for the listed materials, based on the ASTM D139 standard. This article provides data related to "Dielectric Strength Heterogeneity Associated with Printing Orientation in Additively Manufactured Polymer Materials" [1].

The feasibility of inert colloidal processing of silicon nanoparticles.

Silicon nanoparticles have important applications, including nonvolatile floating-gate memory devices. To prevent device performance variations, particle size and oxide thicknesses need to be controlled with a high degree of precision. Additionally, producing well-ordered, two-dimensional arrays of nanoparticles may require the exploitation of self-assembly techniques and colloidal forces, which in turn requires that silicon nanoparticles first come into contact with liquids. Until recently, aerosol silicon nanoparticle collection into liquid was assumed to be an inert process. Once formed, the silicon nanoparticle colloid was assumed to be inert. In fact, silicon nanoparticles produced in the aerosol phase by dilute silane pyrolysis and size classified with a differential mobility analyzer undergo a size reduction upon collection in ethylene glycol, water, and ethanol. Unclassified polydisperse silicon aerosol nanoparticles with an average diameter of 11 nm become monodisperse when collected in a colloid and have a final particle diameter of 2-5 nm. Further evidence suggests that silicon nanoparticles collected in ethanol react with the ethanol to produce tetraalkylorthosilicate-like species. Collections of aerosol silicon nanoparticles in degassed water do not show measurable differences between the aerosol and colloidal size distributions. This reduced reactivity to the solvent indicates that the presence of dissolved oxygen in the solvent may be responsible for the reactivity between the silicon nanoparticles and the solvent.

The Nanomaterial Registry: facilitating the sharing and analysis of data in the diverse nanomaterial community.

The amount of data being generated in the nanotechnology research space is significant, and the coordination, sharing, and downstream analysis of the data is complex and consistently deliberated. The complexities of the data are due in large part to the inherently complicated characteristics of nanomaterials. Also, testing protocols and assays used for nanomaterials are diverse and lacking standardization. The Nanomaterial Registry has been developed to address such challenges as the need for standard methods, data formatting, and controlled vocabularies for data sharing. The Registry is an authoritative, web-based tool whose purpose is to simplify the community's level of effort in assessing nanomaterial data from environmental and biological interaction studies. Because the Registry is meant to be an authoritative resource, all data-driven content is systematically archived and reviewed by subject-matter experts. To support and advance nanomaterial research, a set of minimal information about nanomaterials (MIAN) has been developed and is foundational to the Registry data model. The MIAN has been used to create evaluation and similarity criteria for nanomaterials that are curated into the Registry. The Registry is a publicly available resource that is being built through collaborations with many stakeholder groups in the nanotechnology community, including industry, regulatory, government, and academia. Features of the Registry website (http://www.nanomaterialregistry.org) currently include search, browse, side-by-side comparison of nanomaterials, compliance ratings based on the quality and quantity of data, and the ability to search for similar nanomaterials within the Registry. This paper is a modification and extension of a proceedings paper for the Institute of Electrical and Electronics Engineers.

Nanoinformatics workshop report: Current resources, community needs, and the proposal of a collaborative framework for data sharing and information integration.

The quantity of information on nanomaterial properties and behavior continues to grow rapidly. Without a concerted effort to collect, organize and mine disparate information coming out of current research efforts, the value and effective use of this information will be limited at best. Data will not be translated to knowledge. At worst, erroneous conclusions will be drawn and future research may be misdirected. Nanoinformatics can be a powerful approach to enhance the value of global information in nanoscience and nanotechnology. Much progress has been made through grassroots efforts in nanoinformatics resulting in a multitude of resources and tools for nanoscience researchers. In 2012, the nanoinformatics community believed it was important to critically evaluate and refine currently available nanoinformatics approaches in order to best inform the science and support the future of predictive nanotechnology. The Greener Nano 2012: Nanoinformatics Tools and Resources Workshop brought together informatics groups with materials scientists active in nanoscience research to evaluate and reflect on the tools and resources that have recently emerged in support of predictive nanotechnology. The workshop goals were to establish a better understanding of current nanoinformatics approaches and to clearly define immediate and projected informatics infrastructure needs of the nanotechnology community. The theme of nanotechnology environmental health and safety (nanoEHS) was used to provide real-world, concrete examples on how informatics can be utilized to advance our knowledge and guide nanoscience. The benefit here is that the same properties that impact the performance of products could also be the properties that inform EHS. From a decision management standpoint, the dual use of such data should be considered a priority. Key outcomes include a proposed collaborative framework for data collection, data sharing and information integration.