Separation and measurement techniques for the determination of 228Th, 230Th and 232Th in various matrices

Three analytical techniques are presented which are used at PSI for determination of U and Th isotopes (234U, 235U, 238U, 228Th, 230Th, 232Th) in different materials, i.e. environmental samples (soils, minerals) and dental ceramics as well as in urine for in vitro monitoring of potentially exposed workers. Depending on the sample quantity available and/or required detection limits the measurements are performed either directly via gamma spectrometry or via alpha particle counting with preceding separation chemistry. The separation methods applied are based on either extraction chromatography or on sorption of U and Th on actinide selective resin. Following sample digestion, chemical yield spike additions (232U, 225Th or 225Th), chemical purification and electro-depositional source preparation, alpha particle measurement is carried out using low-level alpha spectrometry. This technique allows detection limits of less than 0.2 mBq per counting source if the assay lasts over a few days and is therefore suitable for determination of trace quantities of short-lived 225Th that can be hardly detected by means of mass spectrometric techniques.     

Optimization of a Microfluidic Mixing Process for Gene Expression-Based Bio-dosimetry

In recent decades advances in radiation imaging and radiation therapy have led to a dramatic increase in the number of people exposed to radiation. Consequently, there is a clear need for personalized biodosimetry diagnostics in order to monitor the dose of radiation received and adapt it to each patient depending on their sensitivity to radiation exposure (Hall E.J. and Brenner D. J., 2008). Similarly, after a large-scale radiological event such as a dirty bomb attack, there will be a major need to assess, within a few days the radiation doses received by tens of thousands of individuals. Current high throughput devices can handle only a few hundred individuals per day. Hence there is a great need for a very fast self-contained non-invasive biodosimetric device based on a rapid blood test.This paper presents a case study where regression methods and designed experiments are used to arrive at the optimal settings for various factors that impact the kinetics in a biodosimetric device. We use ridge regression to initially identify a set of potentially important variables in the mixing process which is one of the critical sub systems of the device. This was followed by a series of designed experiments to arrive at the optimal setting of the significant microfluidic cartridge and piezoelectric disk (PZT) (D. Sadler, F. Zenhausern, U.S. Patent 6,986,601; Lee, S. Y., Ko, B., Yang, W., 2005) related factors. This statistical approach has been utilized to study the microfluidic mixing to mix water and dye mixtures of 70 μl volume. The outcome of the statistical design, experimentation and analysis was then exploited for optimizing the design, fabrication and assembly of the microfluidic devices. As a result of the experiments that were performed, the system was fine tuned and the mixing time was reduced from 5.5 minutes to 2 minutes.     

基于卟啉及其衍生物的硫化氢检测进展

硫化氢既是有毒 物质又是生物体内重要气体信号分子,所以对硫化氢检测的研究十分重要。卟啉及其衍生物作为传感器材料,具有良好的化学稳定性和光学稳定性,与硫化氢结合后会产生光电变化,是检测硫化氢的优良材料。简述了硫化氢的检测手段、卟啉的性质以及卟啉与硫化氢的反应原理,并按照不同的传感器类别综述了卟啉在硫化氢检测中的应用,同时还对卟啉在硫化氢检测的应用领域进行了展望。     

Environmental and risk screening for prioritizing pollution prevention opportunities in the U.S. printed wiring board manufacturing industry

Modern manufacturing of printed wiring boards (PWBs) involves extensive use of various hazardous chemicals in different manufacturing steps such as board preparation, circuit design transfer, etching and plating processes. Two complementary environmental screening methods developed by the U.S. EPA, namely: (i) the Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) and (ii) Risk-Screening Environmental Indicators (RSEI), are used to quantify geographic and chemical environmental impacts in the U.S. PWB manufacturing industry based on Toxics Release Inventory (TRI) data. Although the release weight percentages of industrial chemicals such as methanol, glycol ethers and dimethylformamide comprise the larger fraction of reported air and water emissions, results indicate that lead, copper and their compounds' releases correspond to the highest environmental impact from toxicity potentials and risk-screening scores. Combining these results with further knowledge of PWB manufacturing, select alternative chemical processes and materials for pollution prevention are discussed. Examples of effective pollution prevention options in the PWB industry include spent etchant recovery technologies, and process and material substitutions. In addition, geographic assessment of environmental burden highlights states where promotion of pollution prevention strategies and emissions regulations can have the greatest effect to curb the PWB industry's toxic release impacts.     

Development of a miniature calorimeter for identification and detection of explosives and other energetic compounds

The development of versatile systems capable of providing rapid, portable, and inexpensive detection of explosives and energetic compounds are critically needed to offer enhanced levels of protection against current and future threats to homeland security, as well as satisfying a wide range of applications in the fields of forensic analysis, emergency response, and industrial hazards analysis. Calorimetric techniques have been largely overlooked in efforts to develop advanced chemical analysis technology, largely because of limitations associated with the physical size of the instruments and the relatively long timescales (>30 min) required to obtain a result. This miniaturized calorimeter circumvents these limitations, thereby creating a first-of-its-kind system allowing thermal analysis to be performed in a portable format that can be configured for use in a variety of field operations with a significantly reduced response time (approximately 2 min). Unlike current explosives detectors, this system is based on calorimetric techniques that are inherently capable of providing direct measurements of energy release potential and therefore do not depend on prior knowledge of familiar compounds.     

A review of the U.S. Environmental Protection Agency's Research Program on the prevention and control of hazardous material spills

This paper is a status report on a number of the projects in progress at the Industrial Waste Treatment Research Laboratory of the U.S. Environmental Protection Agency at Edison, New Jersey. The actual causes of numerous hazardous material spills have been documented and analyzed to assign priority to operational areas in which spill prevention and control procedures are urgently needed. Spill alert systems are ready for installation on marginally safe earthen holding pond dikes. Fail-safe systems are being evaluated to reduce spillage from overfilling and from transfer line rupture. The handling of spills in municipalities has been addressed with particular attention to the maintenance and utilization of secondary sewage treatment facilities during spill events.Among the physical and chemical treatment systems that have been or are being produced are trailer-mounted units for processing contaminated water. Also, special devices are being designed for the dispersion and recovery — where necessary — of adsorbents and counteractive chemical reagents for in situ treatment of polluted water bodies. Plastic foams have been developed to dike or confine spills and to plug leaks in ruptured containers. A pickup truck-mounted collection unit, consisting of a battery-powered pump and a self-deploying plastic storage bag, has been constructed and tested.Nearing final testing is a “Sea Curtain”, which extends from the bottom of a stream to the air above. The “Curtain” can be used to isolate a water column that is being contaminated by a soluble, sinking, or floating hazardous material discharged from shore or in stream. Gelling and solidification agents have been shown to be effective in immobilizing spilled hazardous materials. Systems are being built to reprocess treatment agents for reuse and to detoxify whatever agents or recovered materials cannot be salvaged. Field-use packets and other easy-to-deploy items are being developed to trace spills in water and to assess the effectiveness of cleanup. Procedures for enhanced, in-place, biological degradation of spilled hazardous materials are under test.The thrust of the Laboratory's program in these and in related projects is toward the demonstration of practical procedures, hardware, and suitably engineered systems for the prevention and control of spills of hazardous materials.     

A Step-by-Step Approach to Using the SAS™ System for Factor Analysis and Structural Equation Modeling

Radiation detection systems are deployed at U.S. borders to guard against entry of illicit radioactive material. This article uses realistic simulated data under different vehicle and illicit material scenarios to compare the performance of six detection methods for analyzing neutron count data collected as a vehicle passes through a radiation portal monitor, that is, a neutron count vehicle profile. The six methods are based on the cumulative count, the maximum count, sequential cumulative sum, sequential exponentially weighted moving average, comparison against a matched filter (MF) library, and a new estimated MF that estimates the shape of a neutron count vehicle profile.     

Worldwide water standards for hemodialysis

Contaminants commonly found in tap water are toxic to hemodialysis patients. To prevent patient injury from these contaminants, standards for the quality of water used to prepare dialysate have been developed. These standards are in general agreement concerning maximum allowable levels of inorganic chemical contaminants known to have adverse consequences for dialysis patients. There is less agreement about inorganic chemical contaminants that may be toxic, and most standards omit any requirements for organic chemical contaminants. There are considerable differences between standards regarding the maximum allowable levels of microbiological contaminants, as well as the methods to be used for measuring them. Harmonization of existing standards may improve patient protection by promoting demonstrated best practices. Harmonization will require innovation and compromise to produce a standard that is widely applicable, provides patients with the necessary safeguards, and whose requirements can be routinely achieved within the constraints imposed by local reimbursement practices.     

Microfluidic Designing Microgels Containing Highly Concentrated Gold Nanoparticles for SERS Analysis of Complex Fluids

Surface‐enhanced Raman scattering (SERS) is one of the most promising methods to detect small molecules for point‐of‐care analysis as it is rapid, nondestructive, label‐free, and applicable for aqueous samples. Here, microgels containing highly concentrated yet evenly dispersed gold nanoparticles are designed to provide SERS substrates that simultaneously achieve contamination‐free metal surfaces and high signal enhancement and reproducibility. With capillary microfluidic devices, water‐in‐oil‐in‐water (W/O/W) double‐emulsion drops are prepared to contain gold nanoparticles and hydrogel precursors in innermost drop. Under hypertonic condition, water is selectively pumped out from the innermost drops. Therefore, gold nanoparticles are gently concentrated without forming aggregates, which are then captured by hydrogel matrix. The resulting microgels have a concentration of gold nanoparticles ≈30 times higher and show Raman intensity two orders of magnitude higher than those with no enrichment. In addition, even distribution of gold nanoparticles results in uniform Raman intensity, providing high signal reproducibility. Moreover, as the matrix of the microgel serves as a molecular filter, large adhesive proteins are rejected, which enables the direct detection of small molecules dissolved in the protein solution. It is believed that this advanced SERS platform is useful for in situ detection of toxic molecules in complex mixtures such as biological fluids, foods, and cosmetics.     

Incompatibilities of chemicals

Chemical incompatibilities are potentially significant problems where hazardous chemicals are found. A number of chemical segregation systems have been developed which provide recommendations for the separation of incompatible chemicals. Three segregation systems were identified in this study: the UN Dangerous Goods system (which uses physical hazard as the main reason for segregation and has 14 categories), the US CHRIS system (which uses chemical reactivity and has 24 categories) and a third system which uses environmental risks (and has 25 categories). These systems were combined. Merging of each system was initially problematic, but became considerably easier once certain characteristics had been defined (such as flammability or water incompatibility). This gave a final merged incompatibility table containing 100 different segregation groups. This research study showed that it was possible to combine different segregation systems based on different criteria and that more comprehensive segregation systems can be developed. These can be of use in the decision-making process about where groups of chemicals may be used, and during the use of chemicals, where chemicals should not be combined. The use of more comprehensive segregation systems will also assist in developing proper measures for their control.     

Rapid simultaneous ultrasensitive immunodetection of five bacterial toxins

Rapid ultrasensitive detection of gastrointestinal pathogens presents a great interest for medical diagnostics and epidemiologic services. Though conventional immunochemical and polymerase chain reaction (PCR)-based methods are sensitive enough for many applications, they usually require several hours for assay, whereas as sensitive but more rapid methods are needed in many practical cases. Here, we report a new microarray-based analytical technique for simultaneous detection of five bacterial toxins: the cholera toxin, the E. coli heat-labile toxin, and three S. aureus toxins (the enterotoxins A and B and the toxic shock syndrome toxin). The assay involves three major steps: electrophoretic collection of toxins on an antibody microarray, labeling of captured antigens with secondary biotinylated antibodies, and detection of biotin labels by scanning the microarray surface with streptavidin-coated magnetic beads in a shear-flow. All the stages are performed in a single flow cell allowing application of electric and magnetic fields as well as optical detection of microarray-bound beads. Replacement of diffusion with a forced transport at all the recognition steps allows one to dramatically decrease both the limit of detection (LOD) and the assay time. We demonstrate here that application of this "active" assay technique to the detection of bacterial toxins in water samples from natural sources and in food samples (milk and meat extracts) allowed one to perform the assay in less than 10 min and to decrease the LOD to 0.1-1 pg/mL for water and to 1 pg/mL for food samples.     

Direct sampling of chemical weapons in water by photoionization mass spectrometry

The vulnerability of water supplies to toxic contamination calls for fast and effective means for screening water samples for multiple threats. We describe the use of photoionization (PI) mass spectrometry (MS) for high-speed, high-throughput screening and molecular identification of chemical weapons (CW) threats and other hazardous compounds. The screening technology can detect a wide range of compounds at subacute concentrations with no sample preparation and a sampling cycle time of approximately 45 s. The technology was tested with CW agents VX, GA, GB, GD, GF, HD, HN1, and HN3, in addition to riot agents and precursors. All are sensitively detected and give simple PI mass spectra dominated by the parent ion. The target application of the PI MS method is as a routine, real-time early warning system for CW agents and other hazardous compounds in air and in water. In this work, we also present comprehensive measurements for water analysis and report on the system detection limits, linearity, quantitation accuracy, and false positive (FP) and false negative rates for concentrations at subacute levels. The latter data are presented in the form of receiver operating characteristic curves of the form of detection probability P(D) versus FP probability P(FP). These measurements were made using the CW surrogate compounds, DMMP, DEMP, DEEP, and DIMP. Method detection limits (3sigma) obtained using a capillary injection method yielded 1, 6, 3, and 2 ng/mL, respectively. These results were obtained using 1-microL injections of water samples without any preparation, corresponding to mass detection limits of 1, 6, 3, and 2 pg, respectively. The linear range was about 3-4 decades and the dynamic range about 4-5 decades. The relative standard deviations were generally <10% at CW subacute concentrations levels.     

Nuclear detection to prevent or defeat clandestine nuclear attack

Countering clandestinely delivered nuclear and radiological threats requires a multielement, global, civil/military, system-of-systems approach. One important element is geographically layered, sensor-based detection of threat objects, including radiation detection systems. An effective defense against these threats should take advantage of the latest developments in radiation detection technology. This paper reviews the physics of nuclear detection, and points out areas where improvements can be anticipated, via case studies of technologies such as gamma-ray imaging, advanced radiography, large-area detectors, and active interrogation.     

Navy Programs in Superconducting Technology

A review of U.S. Navy efforts in superconducting technology is given. Programs include development of superconducting magnets for motors in ship propulsion systems and to generate magnetic moments in mine sweeping systems. A program to develop superconducting quantum interference devices (SQUIDs) for detection of mines and buried ordnance has successfully been demonstrated. In electronic applications, superconducting filters, resonators, and antennae are being developed for radar, communication, and space systems. Concurrent with these superconductivity programs are efforts to improve the efficiency, reliability, and affordability of refrigeration systems.     

Probe Attack Detection Using an Improved Intrusion Detection System

The novel Software Defined Networking (SDN) architecture potentially resolves specific challenges arising from rapid internet growth of and the static nature of conventional networks to manage organizational business requirements with distinctive features. Nevertheless, such benefits lead to a more adverse environment entailing network breakdown, systems paralysis, and online banking fraudulence and robbery. As one of the most common and dangerous threats in SDN, probe attack occurs when the attacker scans SDN devices to collect the necessary knowledge on system susceptibilities, which is then manipulated to undermine the entire system. Precision, high performance, and real-time systems prove pivotal in successful goal attainment through feature selection to minimize computation time, optimize prediction performance, and provide a holistic understanding of machine learning data. As the extension of astute machine learning algorithms into an Intrusion Detection System (IDS) through SDN has garnered much scholarly attention within the past decade, this study recommended an effective IDS under the Grey-wolf optimizer (GWO) and Light Gradient Boosting Machine (LightGBM) classifier for probe attack identification. The InSDN dataset was employed to train and test the proposed IDS, which is deemed to be a novel benchmarking dataset in SDN. The proposed IDS assessment demonstrated an optimized performance against that of peer IDSs in probe attack detection within SDN. The results revealed that the proposed IDS outperforms the state-of-the-art IDSs, as it achieved 99.8% accuracy, 99.7% recall, 99.99% precision, and 99.8% F-measure.     

Process integration design methods for water conservation and wastewater reduction in industry. Part 3: Experience of industrial application

This paper is Part 3 in a three-part series of papers addressing operational techniques for applying mass integration principles to design in industry with special focus on water conservation and wastewater reduction. The presented techniques derive from merging U.S. and Danish experience with industrial applications of process integration, as a result of a recently established co-operation between the U.S. companies Solutia Inc., Cleaner Process Technologies Inc. and McSwain Engineering Inc. and the Technical University of Denmark. Parts 1 and 2 covered design techniques for any number of wastewater streams containing single and multiple contaminants respectively. Part 3 in this series presents experience from applying methods in industry and also illustrates the work related to each of the steps of the methods and discusses the benefits from the insights provided by each step. The presented experience comprises application in small-scale batch productions in textile dyeing and laundering as well as large-scale continuous productions in chemical industry, and it is documented that the methods are robust and independent of the volume and continuity/discontinuity of the production. Industry's experience with defining the scope of the system and with identifying water flow constraints and water quality constraints is discussed. It is shown how physical constraints for the system design often set a limit for the sophistication of the water recycle network and thereby also a limit for how sophisticated the method for system design should be. Finally, pinch analysis and system designs for water recycling in a practical case study are shown, documenting large water saving potentials and achievements. Electronic Publication     

Reversed phase liquid chromatography of organic hydrocarbons with water as the mobile phase

Reversed phase high-performance liquid chromatography (RP-HPLC) is demonstrated for hydrophobic analytes such as aromatic hydrocarbons using only water as the mobile phase. Achievement of reasonable capacity factors for these types of compounds without the need for toxic and costly organic modifiers in the mobile phase is accomplished by substantially decreasing the phase volume ratio of stationary phase relative to the mobile phase volume and by increasing the polarity of the stationary phase relative to stationary phase materials commonly used for RP-HPLC. Applying a stationary phase of trifluoropropylsiloxane, which is a common gas chromatographic stationary phase material, to nonporous glass microspheres yields a stationary phase with a phase volume ratio reduced by about 2 orders of magnitude as compared to common liquid chromatographic packing materials. As a result, a separation was obtained for hydrophobic organic analytes such as benzene, toluene, ethylbenzene, and isopropylbenzene using a water mobile phase at ambient temperature. A separation of sodium benzoate, benzaldehyde, benzene, and butyrophenone is shown in less than 3 min using a water mobile phase and UV/visible absorbance detection. Additionally, the separation of the ionic surfactant species octyl sulfate and dodecyl sulfate in water in less than 3 min, using unsuppressed conductivity detection, is achieved with a separation mechanism based on interactions with the hydrophobic portion of the surfactant. A water mobile phase offers many potential advantages over traditional mixed aqueous/organic solvent systems. In addition to saving on the cost and expense of buying and disposing of toxic solvents and waste, there is less exposure of the operator to potentially harmful solvents. Increased consistency in reproducing retention times can be expected, since there will not be any variability in solvent strength due to slight variations in mobile phase composition. A water mobile phase produces an environment that should provide an inherent advantage of increased signal-to-noise ratio for detection. Additionally, excellent predictions of the octanol/water partitioning coefficient and aqueous solubility for hydrophobic analytes are obtained from a single measurement of the capacity factor in the water mobile phase.     

Acoustic Trapping: An Emerging Tool for Microfabrication Technology

The high throughput deposition of microscale objects with precise spatial arrangement represents a key step in microfabrication technology. This can be done by creating physical boundaries to guide the deposition process or using printing technologies; in both approaches, these microscale objects cannot be further modified after they are formed. The utilization of dynamic acoustic fields offers a novel approach to facilitate real-time reconfigurable miniaturized systems in a contactless manner, which can potentially be used in physics, chemistry, biology, as well as materials science. Here, the physical interactions of microscale objects in an acoustic pressure field are discussed and how to fabricate different acoustic trapping devices and how to tune the spatial arrangement of the microscale objects are explained. Moreover, different approaches that can dynamically modulate microscale objects in acoustic fields are presented, and the potential applications of the microarrays in biomedical engineering, chemical/biochemical sensing, and materials science are highlighted alongside a discussion of future research challenges.     

Comparative risk assessment: an international comparison of methodologies and results

Comparative risk assessment (CRA) is a systematic procedure for evaluating the environmental problems affecting a geographic area. This paper looks beyond the U.S. border and examines the experience with CRAs conducted in various developing countries and economies in transition, including Bangkok, Thailand, Cairo, Egypt and Quito, Ecuador, as well as other locations in Eastern Europe, Asia and Central and South America. A recent pilot CRA conducted in Taiwan is also considered. Comparisons are made of both the methodologies and the results across the relatively diverse international literature. The most robust finding is that conventional air pollutants (e.g., particulate matter and lead) consistently rank as high health risks across all of the CRAs examined. Given the varied nature of the settings studied in the CRAs, including level of economic development, urban-rural differences, and climate, this finding is particularly significant. Problems involving drinking water are also ranked as a high or medium health risk in almost all the countries studied. This is consistent with the results of analyses conducted by the World Bank suggesting contamination, limited coverage and erratic service by water supply systems.Beyond the major air pollutants and drinking water, the CRA results diverge significantly across countries. A number of problems involving toxic chemicals, e. g., hazardous air pollutants, rank as high health risks in the US but do not appear as consistent areas of concerns in the other countries studied. This likely reflects the so-called "risk transition" - the shift from sanitation and infection disease problems to those involving industry, vehicles and toxic substances - that often occurs with economic development. It may also reflect the greater information about sources of toxic pollutants in the U.S. For other problems, there are important differences across the developing countries and economies in transition. For example, hazardous and (industrial) non-hazardous waste issues ranked as medium or low health risks in all the countries studied, except for Taiwan where unmanaged toxic waste sites were considered to pose high risks. While the generally low ranking is consistent with the notion that few people are directly exposed to hazardous and (industrial) non-hazardous waste, it is not entirely surprising that views might be different in Taiwan, where space is so limited and population density is so high.We suggest that the wide range of findings likely reflect genuine differences among the countries studied. However, we cannot entirely rule out the possibility that some of the observed similarities (and differences) arise from the (relatively) common methodologies employed.     

A contaminant detection system for early warning in water distribution networks

Water distribution systems are spatially diverse. As such, they are inherently vulnerable to accidental or deliberate physical, chemical, or biological threats. Efficient water quality monitoring is one of the most important tools to guarantee a reliable potable water supply. A methodology and two example applications for finding the optimal layout of a detection system, taking explicitly into account the dilution and decay properties of the water quality constituents as distributed with flow, as well as the ability of the monitoring equipment to detect contaminant concentrations, are formulated and demonstrated. The detection system outcome is aimed at capturing contaminant entries within a pre-specified level of service (LOS) defined as the maximum volume of polluted water exposure to the public at a concentration higher than a minimum hazard level. The proposed methodology couples hydraulic simulations with graph theory techniques to identify a minimum set of monitoring stations that ‘covers’ the entire network for a given LOS, at a maximum degree of system invulnerability. The model developed extends a previous work of the authors through explicitly considering the deterioration and dilution of water quality as distributed with flow, and by taking into account the monitoring equipment capabilities to detect pollutant concentrations. The methodology is demonstrated using two example applications.