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Particulate transport from surfaces governs a variety of phenomena including fungal spore dispersal, bioaerosol transmission, and self-cleaning. Here, we report a previously unidentified mechanism governing passive particulate removal from superhydrophobic surfaces, where a particle coalescing with a water droplet (similar to 10 to similar to 100 mu m) spontaneously launches. Compared to previously discovered coalescence-induced binary droplet jumping, the reported mechanism represents a more general capillary-inertial dominated transport mode coupled with particle/droplet properties and is typically mediated by rotation in addition to translation. Through wetting and momentum analyses, we show that transport physics depends on particle/droplet density, size, and wettability. The observed mechanism presents a simple and passive pathway to achieve self-cleaning on both artificial as well as biological materials as confirmed here with experiments conducted on butterfly wings, cicada wings, and clover leaves. Our findings provide insights into particle-droplet interaction and spontaneous particulate transport, which may facilitate the development of functional surfaces for medical, optical, thermal, and energy applications.

3D microfluidic networks are fabricated in a gelatin hydrogel using sacrificial melt-spun microfibers made from a material with pH-dependent solubility. The fibers, after being embedded within the gel, can be removed by changing the gel pH to induce dissolution. This process is performed in an entirely aqueous environment, avoiding extreme temperatures, low pressures, and toxic organic solvents. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

3D microfluidic networks are fabricated in a gelatin hydrogel using sacrificial melt-spun microfibers made from a material with pH-dependent solubility. The fibers, after being embedded within the gel, can be removed by changing the gel pH to induce dissolution. This process is performed in an entirely aqueous environment, avoiding extreme temperatures, low pressures, and toxic organic solvents. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A device containing a 3D microchannel network (fabricated using sacrificial melt-spun microfibers) sandwiched between lithographically patterned microfluidic channels offers improved delivery of soluble compounds to a large volume compared to a simple stack of two microfluidic channel layers. With this improved delivery ability comes an increased fluidic resistance due to the tortuous network of small-diameter channels., United States. Army (Engineer Research and Development Center-Construction Engineering Research Laboratory (ERDC-CERL)), National Institutes of Health (U.S.) (NIH grant 5F32EB011866), National Institutes of Health (U.S.) (NIH Grant 1K99EB013630), National Institutes of Health (U.S.) (NIH NHLBI grant 1 R21 HL106585-01), National Heart, Lung, and Blood Institute (NIH NHLBI grant 1 R21 HL106585-01)

Perchlorate is a pervasive water contaminant that has drawn national attention as a public health concern. Although perchlorate contamination has both natural and anthropogenic origins, its recurrent use in military munitions makes perchlorate the highest-priority military pollutant. Currently, perchlorate detection at the critical parts-per-billion level requires large, sophisticated instrumentation in a centralized laboratory. This report describes a fieldable, microchip capillary electrophoresis (MCE) device that is selective for perchlorate and exhibits reduced analysis times and reagent consumption. The device employs contact conductivity detection and zwitterionic surfactant chemistry to selectively resolve perchlorate from abundant environmental species such as chloride, nitrate, and sulfate. The prototype MCE system is capable of detection limits of 3.4 + or - 1.8 ppb in standards and 5.6 + or - 1.7 ppb in drinking water. Additional work modified the microchip geometry and separation chemistry, to account for higher ionic strength sample matrices such as surface and ground water, which cause interferences with perchlorate detection. A novel extraction method, incorporating the fundamentals of electrostatic ion chromatography (EIC), is presented as a way to overcome this challenge. Two extraction formats, employing either a packed bed or a monolith, were also investigated and presented in this work., The original document contains color images.

Due to the numerous toxicological effects of lead, its presence in the environment needs to be effectively monitored. Incorporating a biosensing element within a microfluidic platform enables rapid and reliable determinations of lead at trace levels. This work pro-duced a microchip-based lead sensor that employs a lead-specific DNAzyme (also called catalytic DNA or deoxyribozyme) as a recognition element that cleaves its complementary substrate DNA strand only in the presence of cationic lead (Pb2+). Fluorescent tags on the DNAzyme translate the cleavage events to measurable, optical signals proportional to Pb2+ concentration. The DNAzyme responds sensitively and selectively to Pb2+, and immobilizing the DNAzyme in the sensor permits both sensor regeneration and lo-calization of the detection zone. The immobilized DNAzyme retains its Pb2+ detection activity in the microfluidic device and can be regenerated and reused. The particular DNAzyme shows no response to other common metal cations and the presence of these con-taminants does not interfere with the lead-induced fluorescence signal. Attempts were made to incorporate a second DNAzyme with selectivity for uranium in the same microfluidic chip sensor, to demonstrate multiplexing capabilities for multiple metal analytes in a single injection. Crosstalk between the lead DNAzyme and the uranium DNAzyme severely limited the utility of this multi-analytic chip., Prepared in cooperation with the Univ of Illinois Depts of Chemistry and Chemical and Biomolecular Engineering, Urbana.

There is a consistent demand for new biosensors for the detection of protein targets, and a systematic method for the rapid development of new sensors is needed. Here we present a platform where short unstructured peptides that bind to a desired target are selected using M13 phage display. The selected peptides are then chemically synthesized and immobilized on gold, allowing for detection of the target using electrochemical techniques such as electrochemical impedance spectroscopy (EIS). A quartz crystal microbalance (QCM) is also used as a diagnostic tool during biosensor development. We demonstrate the utility of this approach by creating a novel peptide-based electrochemical biosensor for the enzyme alanine aminotransferase (ALT), a well-known biomarker of hepatotoxicity. Biopanning of the M13 phage display library over immobilized ALT, led to the rapid identification of a new peptide (ALT5-8) with an amino acid sequence of WHWRNPDFWYLK. Phage particles expressing this peptide exhibited nanomolar affinity for immobilized ALT (Kd,app+/-85620 nM). The newly identified ALT5-8 peptide was then chemically synthesized with a C-terminal cysteine for gold immobilization. The performance of the gold-immobilized peptides was studied with cyclic voltammetry (CV), QCM and EIS. Using QCM, the sensitivity for ALT detection was 8.960.9 Hz/(micrograms/mL) and the limit of detection (LOD) was 60 ng/ mL. Using EIS measurements, the sensitivity was 142 +/-12 impedance percentage change %/(mg/mL) and the LOD was 92 ng/mL. In both cases, the LOD was below the typical concentration of ALT in human blood. Although both QCM and EIS produced similar LODs, EIS is preferable due to a larger linear dynamic range. Using QCM, the immobilized peptide exhibited a nanomolar dissociation constant for ALT (Kd = 20.1+/-0.6 nM). These results demonstrate a simple and rapid platform for developing and assessing the performance of sensitive, peptide-based biosensors for new protein targets., Pub. in PLoS One, v6 n10, p1-9, Oct 2011.

Organized cellular alignment is critical to controlling tissue microarchitecture and biological function. Although a multitude of techniques have been described to control cellular alignment in 2D, recapitulating the cellular alignment of highly organized native tissues in 3D engineered tissues remains a challenge. While cellular alignment in engineered tissues can be induced through the use of external physical stimuli, there are few simple techniques for microscale control of cell behavior that are largely cell-driven. In this study we present a simple and direct method to control the alignment and elongation of fibroblasts, myoblasts, endothelial cells and cardiac stem cells encapsulated in microengineered 3D gelatin methacrylate (GelMA) hydrogels, demonstrating that cells with the intrinsic potential to form aligned tissues in vivo will self-organize into functional tissues in vitro if confined in the appropriate 3D microarchitecture. The presented system may be used as an in vitro model for investigating cell and tissue morphogenesis in 3D, as well as for creating tissue constructs with microscale control of 3D cellular alignment and elongation, that could have great potential for the engineering of functional tissues with aligned cells and anisotropic function., Pub. in Biomaterials, p1-11, 2010. Sponsored in part by National Institutes of Health, National Science Foundation CAREER Award (DMR0847287) and U.S. Army Construction Engineering Research Laboratory, Engineering Research and Development Center.

A better understanding of the conformational changes exhibited by intrinsically disordered proteins is necessary as we continue to unravel their myriad biological functions. In repeats in toxin (RTX) domains, calcium binding triggers the natively unstructured domain to adopt a ? roll structure. Here we present an in vitro Foerster resonance energy transfer (FRET)-based method for the investigation of the conformational behavior of an RTX domain from the Bordetella pertussis adenylate cyclase consisting of nine repeat units. Equilibrium and stopped-flow FRET between fluorescent proteins, attached to the termini of the domain, were measured in an analysis of the end-to-end distance changes in the RTX domain. The method was complemented with circular dichroism spectroscopy, tryptophan fluorescence, and bis-ANS dye binding. High ionic strength was observed to decrease the calcium affinity of the RTX domain. A truncation and single amino acid mutations yielded insights into the structural determinants of beta roll formation. Mutating the conserved Asp residue in one of the nine repeats significantly reduced the affinity of the domains for calcium ions. Removal of the sequences flanking the repeat domain prevented folding, but replacing them with fluorescent proteins restored the conformational behavior, suggesting an entropic stabilization. The FRET-based method is a useful technique that complements other low-resolution techniques for investigating the dynamic conformational behavior of the RTX domain and other intrinsically disordered protein domains., Pub. in Biochemistry, v48, p11273-11282, 2009.

This research report describes actual field deposition and laboratory bench-scale applications of military smokes and obscurants (S&O) onto aquatic surfaces to study direct and indirect toxicological effects on threatened and endangered fish species, surrogate fish species, insect prey and aquatic plant habitat. Data allow predictions of impacts, effects, and mortality on relevant aquatic species from exposure to varying concentrations of S&O. Insect prey mortality is observed during relevant field deposition while heavier doses are required to induce lethal and sub-lethal effects on higher order organisms. Modes of toxicity include both direct contact of an organism with surface films and chemical transformation of S&O components into more toxic byproducts via photolytic mechanism upon exposure to sunlight. Recommendations for S&O field use are provided based on conservative estimates of chemical deposition from environmental release of S&O during military training exercises.

The mobile warfighter needs sensor technology that provides an immediate and unambiguous response to toxins in water. Heavy metals are a ubiquitous and troublesome class of pollutants, and lead (Pb) occupies a prominent position as a contaminant requiring constant attention. Especially due to its nature of its toxicity to humans and the environment, persistency, and bioaccumulation, anthropogenic sources of Pb from military operations require active monitoring and sensing to ensure soldier health protection and environmental compliance. We have created a selective and sensitive miniature sensor for Pb2+ by combining two significant advances: (a) catalytic DNA that is reactive only to Pb2+ and (b) nanoscale fluidic molecular gates that can manipulate fluid flows and perform molecular separations on tiny volumes of material., See also ADM002075., The original document contains color images.

Gas chromatography/mass spectrometry was used to analyze the pyrolytic byproducts from an Army-unique propellant compound (AA2) that is composed of predominantly nitrocellulose and nitroglycerin. Compounds produced by AA2 pyrolysis were compared to compounds detected in the gaseous effluent from AA2 incineration. The light permanent gases and most of the higher molecular weight byproducts produced by AA2 incineration are replicated by laboratory pyrolysis on AA2. The reverse case also holds whereby 18 out of 24 high molecular weight AA2 pyrolytic byproducts are found in the incinerator emissions. Poor matching, however, was obtained between the two processes for the volatile, water-soluble species. None of these low molecular weight compounds produced under pyrolytic conditions were detected in the AA2 incinerator samples, likely indicating inefficient capture of these compounds from the effluent stream. Separate pyrolytic degradation of the individual components of AA2 provides evidence that nearly all of the incomplete combustion products detected during incineration originate not from the prevalent energetic ingredients but rather from the minor and trace additives in AA2. In addition, pyrolysis successfully identified the AA2 components capable of surviving the incineration process intact. This work illustrates the potential of bench-scale pyrolysis for predicting incineration behavior.

Pyrolysis is the thermal decomposition of a substance into a variety of by-products, usually in the absence of oxygen. Pyrolysis experiments comparing the behavior of AA2 with the behavior of individual constituents of AA2 provide an excellent example of the additive property that sometimes exists during thermal degradation of composites. The origin of each pyrolytic by-product from AA2 can be deduced by examining set of pyrolysis products from each constituent. Good matching between pyrolytic and incineration data can support using laboratory pyrolysis to predict incineration behavior. Samples of original AA2 from an Army installation were collected for analysis. In addition, chemical standards were obtained for the major components of AA2. All samples and standards were subjected to pyrolysis and the by-products were analyzed by gas chromatography/mass spectrometry.

Incineration is one technology used for thermal treatment of energetic materials (EM) and associated energetic wastes (EW). Knowledge of the by-products from incineration is invaluable for the proper design of emission control systems and selection of operating parameters to ensure maximum destruction efficiency. This project focuses on uncovering the by-products resulting from the incineration of EM and EW. The sampling and analysis of by-products from a hazardous waste incinerator were performed at an Army installation during the burning of several Army waste streams. The three EW burned at this rotary kiln incinerator are nitrocellulose (NC) fines, nitroglycerin (NO) slums, and AA2, a solventless double base propellant. Combustion by-products were collected from a sampling port located between the rotary kiln and incinerator afterburner, upstream of all pollution control devices. Several different sample collection trains were used for characterization of the by-products including volatile and semi-volatile organic compounds, hydrogen cyanide, carbon monoxide, nitrogen oxides, and total hydrocarbons. The collection plan, the instrumental set-up, and the analytical results are presented for the incineration of all three EW listed above. The challenges and problems encountered during sample collection at the incinerator kiln port are discussed as well as solutions used to overcome these problems.

Heavy metal (HM) contaminated waste is a major concern to Army and Department of Defense (DoD) installations due to the total volume and number of sites with this type of waste. The U.S. Environmental Protection Agency (EPA) strictly regulates the disposal and treatment of hazardous waste under the Resource Conservation and Recovery Act (RCRA), which classifies the HM-contaminated waste as hazardous by either definition (e.g., listed) or characteristic. By performing the Toxicity Characteristic Leaching Procedure (TCLP), wastes are tested to determine the leachable contaminant content to decide whether the samples fall within the strict EPA requirements for treatment of hazardous wastes. The vendor products in this testing were used as received for stabilization of standard wastes with the generic procedure provided by the manufacturer. These tests showed that the stabilization can depend on a number of factors, including the initial amount of free metal available to leach, the form of the solid matrix, the total amount of all metals (co-contaminants), and the pH, stressing the need for complete testing of a stabilization product with a particular waste to evaluate the product's performance.

Nitroaromatic compounds with energetic characteristics are frequently present in waste streams produced at U.S. Army facilities. Previous work on the sonolytic destruction of nitroaromatic species in aqueous solutions involved primarily denitration together with oxidation via hydroxyl radical attack. Subjecting a chemical reaction to ultrasound, with frequencies roughly between 15 kHz and 10 MHz, can have a drastic effect. Ultrasound causes acoustic cavitation - the creation, growth, and collapse of bubbles in the solution. The collapse produces localized spots of extreme conditions including temperatures as high as 5000 K and pressures near 1000 atmospheres. The extreme conditions thus created initiate three distinct destruction pathways for organic contaminants: oxidation by hydroxyl radicals, supercritical water oxidation, and pyrolysis. These three mechanisms account for the degradation mechanisms for organic species in water. Interest in ultrasound for decontamination arises from its ability to cause these effects relatively inexpensively, with simple equipment and without severe experimental conditions. In this report, a simple mechanical manipulation of the experimental apparatus is shown to greatly alter the degradation pathway to promote reduction of the nitro group rather than oxidation of the aromatic ring. This work describes this experimental change and demonstrates the sonochemical reduction of nitrobenzene.

The Construction Engineering Research Laboratory (CERL) is developing technologies for the safe, economically advantageous, and environmentally benign assessment, decontamination, and disposal of excess energetic material (EM) processing buildings at U.S. Army Ammunition Plants. Because of a lack of information regarding the possible interactions between asbestos-containing building materials and EMs, CERL began research efforts to determine the nature and extent of adsorption of common energetic compounds on chrysotile asbestos. The adsorption of the nitrate esters, nitroglycerin (NG) and pentaerythritol tetranitrate (PETN), on chrysotile were selected for this initial study. Infrared spectroscopy was used as the principal analytical probe.

Nitrocellulose (NC) fines are the small polymer fibers of NC that are not separable from the NC production stream by settling or centrifugation. Wastewater containing NC fines at a concentration of 150 to 400 parts per million is one of the largest volume waste streams produced by the Army. Current methods of control and disposal depend upon the lack of strict regulations regarding the environmental release of NC fines. Possible changes in the interpretation of state regulations would create immediate disposal problems. Numerous research efforts have investigated NC treatment methods from the novel to the mundane. This report provides data on the effects of high intensity ultrasound on NC degradation in water. The results indicate that NC is resistant to depolymerization and denitration by sonolytic means.

The Army is continually faced with the disposal or treatment of media contaminated with heavy metals such as lead, chromium, and cadmium. The types of media are varied and include soils, ashes, and sludges. Waste having a leachable metal concentration above the Toxicity Characteristic Leaching Procedure limit established by the U.S. Environmental Protection Agency can be treated to render it non-hazardous. Several stabilization/solidification (S/S) processes are used for the treatment of hazardous wastes. Vitrification, for example, incorporates hazardous waste into glass, but the high temperatures needed to make the glass are undesirable. Sol-gel chemistry is a means to make glass at low temperatures. Also, the heavy metals can be chemically incorporated in the glass matrix rather than merely encapsulated. This work examines the ability of sol-gel chemistry to replace vitrification as an S/S technique. A recipe was formulated for immobilizing lead in glass by the sol-gel process. The merits of the process are discussed. Results showed that sol-gel processing stabilized some lead from solutions and encapsulated some metals in a glass matrix. However, sol-gel was found to be too sensitive to chemistry, too limited in application, and too expensive to compete with current S/S processes.

The Army generates many unique types of wastes, primarily because of their explosive and toxic characteristics. For example, the production and handling of 2,4,6-trinitrotoluene creates three types of nitroaromatic waste streams. Treatment technologies that serve the private community typically cannot handle them. The variety of these waste streams together with some highly visible problem areas have stimulated the study of nitroaromatic compound degradation. New chemical treatment methods often involve new methods of producing the highly reactive hydroxyl radical. Since one of the effects of sonolysis on water is the breakdown of water to produce hydroxyl radicals, this work studied sonochemistry as a destruction method for nitroaromatic species in water.

The armaments industry generates approximately 1600 tons per year of hazardous waste containing explosives and propellants. By far, the most common disposal method for this hazardous waste is open burning/open detonation (OB/OD). Unfortunately, OB/OD has the potential to create environmental problems due to uncontrolled emission of by-products. Incineration is currently the most mature and well-characterized alternative disposal technology. In the event that OB/OD is curtailed or even eliminated, studies examining incineration as a back-up treatment technology could have an immediate impact on mission readiness, especially if the focus of the work is on characterization and reduction of emissions. The objective of this work was to examine the pyrolysis of energetic materials and to study the by-products produced during thermal decomposition in the absence of oxygen. Pyrolytic by-products from RDX, TNT, and PETN were examined. Samples were prepared and analyzed, results were studied and compared with work done in previous studies, and recommendations for further research were made.

The U.S. Army maintains a large inventory of buildings treated with lead-based paint (LBP). LBP abatement and disposal is problematic. The residual waste from LBP removal often contains enough lead to be considered a hazardous waste, thereby requiring special handling and disposal. Associated higher costs of worker protection and waste disposal prohibit the use of traditional paint removal methods for removing LBP. A recently developed proprietary product--Blastox(registered)--consists of a material, which, when added to a typical abrasive medium, creates an "engineered abrasive" that is suitable for removal of lead-based paint systems from most surfaces and that, when water is added, also chemically stabilizes the lead in the residual waste so that the waste does not exhibit the Resource Conservation and Recovery Act (RCRA) toxicity characteristic for lead. This investigation evaluated the performance and cost-effectiveness of using Blastox(registered) for removing LBP from wood and steel structures, and for stabilizing the residual waste material. Both laboratory and field evaluations confirmed the feasibility and cost-effectiveness of using Blastox to remove and stabilize LBP.