Detection Of Hazardous Materials Research Articles

A Waveguide Made of Hot Air

During the cold war, politicians spoke of weapon technologies that seemed to come from science fiction [1], including high-power laser beams for fighting remote battles in the sky. The ability to transmit a powerful laser beam through the atmosphere to a distant location—albeit for friendlier purposes—may become reality thanks to the latest discovery by Howard Milchberg and his colleagues at the University of Maryland in College Park. In Physical Review X, they demonstrate that a laser beam can be efficiently channeled through a gas and arrive at its destination with a much higher average power than was previously thought possible [2]. Their trick is to use a square-shaped bundle of four intense filaments of light that leave behind a trail of hot gas: The four hot air columns expand and create a central zone of higher-density air that serves as a waveguide for subsequent pulses of light. The researcher’s method could be used to direct laser energy to remote locations, providing a new way to, for instance, nudge space debris out of Earth’s orbit. Other applications include the remote detection of radioactive or hazardous materials and atmospheric laser communications.

Recent advances in the application of high performance capillary electrophoresis for food safety

In recent years, food safety incidents become a serious social problem. Foods are usually complex mixtures consisting of a large diversity of molecules. Analysis of foods is a topic that demands the development of rapid, robust, efficient, sensitive and cost-effective analytical methodologies. Therefore, new techniques for food safety purpose are required by analytical chemists. Capillary electrophoresis (CE) is a popular separation technique that possesses fast and efficient performances in an automated way with minimum consumption of sample and reagents. Nowadays, CE represents a desired strategy for the determination of many compounds or molecules in various kinds of food. In this paper, the review intends to provide the recent innovative developments reported in food safety analysis using CE methods for a full overview. As a fundamental review, it focuses on the introduction and detection of several common hazardous materials existing in food such as non-food additives, pesticide residues, veterinary drug residues, heavy metal ion contaminants, toxins, biphenol A and phthalates in packaging materials and so on. Furthermore, this review prospects the main development direction of CE in this field for the future. A total of 63 papers published during the period of Jan 2009 - Jun 2012 are included in the present review.

Ant Colony Based Path Planning Algorithm for Autonomous Robotic Vehicles

The requirement of an autonomous robotic vehicles demand highly efficient algorithm as well as software. Today’s advanced computer hardware technology does not provide these types of extensive processing capabilities, so there is still a major space and time limitation for the technologies that areavailable for autonomous robotic applications. Now days, small to miniature mobile robots are required for investigation, surveillance and hazardous material detection for military and industrial applications. But these small sized robots have limited power capacity as well as memory and processing resou rces. A number of algorithms exist for producing optimal path for dynamically cost. This paper presents a new ant colony based approach which is helpful in solving path planning problem for autonomous robotic application. The experiment of simulation verified its validity of algor ithm in terms of time.

Vaporation characteristics of low-melting nitrocompounds by isothermal thermogravimetry

Determination of vapor pressure is critical for accurate detection of trace volatile hazardous materials, ensuring human health and environmental security. 2,4,6-Trinitrotoluene (TNT), 3,4-Dinitrofurazanfuroxan (DNTF), and 2,4-Dinitroanisole (DNAN) are an important class of volatile low-melting nitrocompounds which are widely used in military, aerospace, and defense industry. In this study, the sublimation and evaporation characteristics of these three nitrocompounds were investigated for the first time by using isothermal thermogravimetry (TG) undergoing zero order, non-activated evaporation processes, analyzed with the Antoine and Langmuir equations, and confirmed with benzoic acid as a calibration material. The Clausius–Clapeyron equations of TNT, DNTF, and DNAN at both sublimation and evaporation processes are established using the temperature dependence of vapor pressure. The enthalpies of sublimation and evaporation are determined. The results of TNT are well consistent with literatures, proving that the isothermal TG for determination of vapor pressure is eligible and accurate. This work lays the foundation for further study of the reliable trace detection of hazardous low-melting nitrocompounds.

Rapid Estimation of Thermodynamic Parameters and Vapor Pressures of Volatile Materials at Nanoscale

Non-isothermal measurements of thermodynamic parameters and vapor pressures of low-volatile materials are favored when time is a crucial factor to be considered, such as in the case of detection of hazardous materials. In this article, we demonstrate that optical absorbance spectroscopy can be used non-isothermally to estimate the thermodynamic properties and vapor pressures of volatile materials with good accuracy. This is the first method to determine such parameters in nanoscale in just minutes. Trinitrotoluene (TNT) is chosen because of its low melting temperature, which makes it impossible to determine its thermodynamic parameter by other rising-temperature techniques, such as thermogravimetric analysis (TGA). The well-characterized vapor pressure of benzoic acid is used to calibrate the spectrometer in order to determine the vapor pressure of low-volatile TNT. The estimated thermodynamic properties of both benzoic acid and TNT are in excellent agreement with the literature. The estimated vapor pressure of TNT is one order of magnitude larger than that determined isothermally using the same method. However, the values are still within the range reported in the literature. The data indicate the high potential for use of rising-temperature absorbance spectroscopy in determining vapor pressures of materials at nanometer scale in minutes instead of hours or days.

Characterization of Polymorphic States in Energetic Samples of 1,3,5-Trinitro-1,3,5-Triazine (RDX) Fabricated Using Drop-on-Demand Inkjet Technology

The United States Army and the first responder community are evaluating optical detection systems for the trace detection of hazardous energetic materials. Fielded detection systems must be evaluated with the appropriate material concentrations to accurately identify the residue in theater. Trace levels of energetic materials have been observed in mutable polymorphic phases and, therefore, the systems being evaluated must be able to detect and accurately identify variant sample phases observed in spectral data. In this work, we report on the novel application of drop-on-demand technology for the fabrication of standardized trace 1,3,5-trinitro-1,3,5-triazine (RDX) samples. The drop-on-demand sample fabrication technique is compared both visually and spectrally to the more commonly used drop-and-dry technique. As the drop-on-demand technique allows for the fabrication of trace level hazard materials, concerted efforts focused on characterization of the polymorphic phase changes observed with low concentrations of RDX commonly used in drop-on-demand processing. This information is important when evaluating optical detection technologies using samples prepared with a drop-on-demand inkjet system, as the technology may be "trained" to detect the common bulk α phase of the explosive based on its spectral features but fall short in positively detecting a trace quantity of RDX (β-phase). We report the polymorphic shifts observed between α- and β-phases of this energetic material and discuss the conditions leading to the favoring of one phase over the other.

Bacterial biofilm-based water toxicity sensor

Cell-based toxicity bioassays harbor the potential for efficient detection and monitoring of hazardous materials. However, their use in the field has been limited by harsh and unstable environmental conditions that shorten shelf-life, introduce significant noise, and reduce the signal and signal-to-noise ratio; such conditions may thus decrease the probability of correct decisions, increasing both false positive and false negative outcomes. Therefore, there is a need for a stable cell-on-chip integration that offers long-term storage and resilience to environmental factors. The use of intact microbial biofilms as biological elements in a whole-cell biosensor, and their integration into specialized biochips, holds promise for enhancing sensor stability as well as providing an innovative platform for biofilm research. We report here for the first time on the integration of a bacterial biofilm as the sensing element of a whole-cell biosensor, as a means to stabilize and preserve reproducibility, viability and functionality of the bacterial sensor cells. We have employed a genetically engineered Escherichia coli sensor strain, tailored to respond to the presence of genotoxic (DNA damaging) agents by the induction of a reporter enzyme, alkaline phosphatase, and tested its functionality in colorimetric and electrochemical assays. Three different bacterial integration forms were examined: planktonic cells, electronically deposited sessile cells, and biofilms. For all integration forms, a clear dose-dependent positive response to the presence of the model toxicant nalidixic acid was observed, with biofilms displaying higher current density and detection sensitivity than planktonic and sessile cells. We present the electrode apparatus and methods and biochip characterization of such chips, e.g. signal vs. time and induction factor, and discuss the advantage and potential problems of the new biofilm-biochip technology.

Switched Ferroelectric Plasma Ionizer (SwiFerr) for Ambient Mass Spectrometry

We present the implementation of a switched ferroelectric plasma ionizer (SwiFerr) for ambient analysis of trace substances by mass spectrometry. The device utilizes the ferroelectric properties of barium titanate (BaTiO(3)) to take advantage of the high electric field resulting from polarization switching in the material. The source comprises a [001]-oriented barium titanate crystal (5 × 5 × 1 mm) with a metallic rear electrode and a metallic grid front electrode. When a high voltage AC waveform is applied to the rear electrode to switch polarization, the resulting electric field on the face of the crystal promotes electron emission and results in plasma formation between the crystal face and the grounded grid at ambient pressure. Interaction with this plasma and the resulting reagent ions effects ionization of trace neutrals. The source requires less than 1 W of power to operate under most circumstances, ionizes molecules with acidic and basic functional groups easily, and has proven quite versatile for ambient analysis of both vapor phase and aspirated powdered solid samples. Ionization of vapor phase samples of the organics triethylamine, tripropylamine, tributylamine, and pyridine results in observation of the singly protonated species in the positive ion mass spectrum with sensitivity extending into the high ppb range. With acetic acid, deprotonated clusters dominate the negative ion mass spectrum. Aerodynamic sampling of powdered samples is used to record mass spectra of the pharmaceuticals loperamide and ibuprofen. Chemical signatures, including protonated loperamide and deprotonated ibuprofen, are observed for each drug. The robust, low power source lends itself easily to miniaturization and incorporation in field-portable devices used for the rapid detection and characterization of trace substances and hazardous materials in a range of different environments.

Improved estimation of local background covariance matrix for anomaly detection in hyperspectral images

Anomaly detection in hyperspectral images has proven valuable in many applications, such as hazardous material and mine detection. The benchmark anomaly detector is the Reed-Xiaoli (RX) detector, which is based on the local multivariate normality of background. The RX algorithm, along with its many modified versions, has been widely explored, and the main concerns identified are related to local background covariance matrix estimation. The small sample size, local background nonhomogeneity, and the presence of target pixels within the estimation window are factors that can deeply affect local background covariance matrix estimation. These critical aspects may occur together in the same operational scenario, and they may strongly impair the detection performance. However, due to their intrinsic difference, these aspects have been typically discussed within different frameworks, disregarding the possible existing connections while developing different approaches to solution. We investigate these critical aspects, along with their impact on the detection process, from an operational detection perspective. The approaches to solution are critically analyzed, discussing possible links and connections. Real hyperspectral data are employed for assessing if the algorithms, designed ad hoc to solve a specific problem, can either handle more complex situations, or bring about further complications.

Investigation of the PGNAA using the LaBr3 scintillation detector

The Joint Research Centre of the European Commission develops instrumentation for detection of hazardous materials. In relation to this a new experimental facility was constructed for research into methods applying the detection of characteristic gamma rays subsequent to neutron irradiation. This includes the detection of prompt gamma rays from neutron inelastic scattering and neutron capture. For this purpose the device employs LaBr(3) scintillation detectors. The paper investigates the applicability of the LaBr(3) scintillation detector to PGNAA.

A multisignal detection of hazardous materials for homeland security

The detection of hazardous materials has been identified as one of the most urgent needs of homeland security, especially in scanning cargo containers at United States ports. To date, special nuclear materials have been detected using neutron or gamma interrogation, and recently the nuclear resonance fluorescence has been suggested. We show a new paradigm in detecting the materials of interest by a method that combines four signals (radiography/computer tomography, acoustic, muon scattering, and nuclear resonance fluorescence) in cargos. The intelligent decision making software system is developed to support the following scenario: initially, radiography or the computer tomography scan is constructed to possibly mark the region(s) of interest. The acoustic interrogation is utilized in synergy to obtain information regarding the ultrasonic velocity of the cargo interior. The superposition of the computer tomography and acoustic images narrows down the region(s) of interest, and the intelligent system guides the detection to the next stage: no threat and finish, or proceed to the next interrogation. If the choice is the latter, knowing that high Z materials yield large scattering angle for muons, the muon scattering spectrum is used to detect the existence of such materials in the cargo. Additionally, the nuclear resonance fluorescence scan yields a spectrum that can be likened to the fingerprint of a material. The proposed algorithm is tested for detection of special nuclear materials in a comprehensive scenario.

Elemental Analysis of Neutron-Induced Gamma-Ray Spectra for Detection of Hazardous Materials

Elemental analysis of neutron-induced gamma-ray spectra is a significant technology in the detection of chemical agents, explosives, etc. The hard part of this problem is the very complicated and uncertain background signals of the gamma-ray spectra. Also, the background signals are always changing as the searched objects change, thus further complicating the gamma-ray spectra analysis process. We can define a typical or average background spectrum if the variation of background spectrum is not too large, then we use this background spectrum to identify a gamma-ray signal.We tested both the direct summation approach and the Gaussian fitting approach in our computer algorithms. We found these two different approaches have individual advantages and disadvantages when they are applied in calculations of the signal significance level. In the end, we combined the direct summation approach with the Gaussian fitting approach in our computer algorithms in the actual calculations of the signal significance level.Based on our previous preliminary MCNP simulations results, we used phosphorus powder to simulate the chemical agent sarin and used our automated computer algorithms to calculate the single-line and multiple-line signal significance levels. Presented in this paper are some results in which we used our experimental data to test our average background spectrum and our computer algorithms. Our calculated results show the average background spectra that we defined are appropriate for the elemental analysis in searching for the chemical agent, and our computer algorithms, in which we combined the direct summation approach with the Gaussian fitting approach, function well. From a multiple-line analysis, our calculated results show that in the real application of this neutron-induced gamma-ray detection technique the detection time can be reduced to 15 s or less for detecting small quantities of chemical agents.

Improvement of the Robotic System for Disaster and Hazardous Threat Management

Following paper shows an improvement of the robotic system (Masłowski, 2004 and 2006) for disaster and hazardous threat management. The system uses two types of robots for investigating the potential risks in unknown environment – teleoperated and fully autonomous mobile platform. The teleoperated robot equipped with video cameras and 5DOF arm is used for hazardous materials detection and neutralization. The improvement is based on the autonomous mobile robot development based on hybrid composition of 3D laser scanners providing 3D feedback to base station. The idea of real time 3D map building is shown. The new idea of the usage given map to the supervision module of the robotics system is presented.

Standoff Detection of Chemical and Biological Threats Using Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a promising technique for real-time chemical and biological warfare agent detection in the field. We have demonstrated the detection and discrimination of the biological warfare agent surrogates Bacillus subtilis (BG) (2% false negatives, 0% false positives) and ovalbumin (0% false negatives, 1% false positives) at 20 meters using standoff laser-induced breakdown spectroscopy (ST-LIBS) and linear correlation. Unknown interferent samples (not included in the model), samples on different substrates, and mixtures of BG and Arizona road dust have been classified with reasonable success using partial least squares discriminant analysis (PLS-DA). A few of the samples tested such as the soot (not included in the model) and the 25% BG:75% dust mixture resulted in a significant number of false positives or false negatives, respectively. Our preliminary results indicate that while LIBS is able to discriminate biomaterials with similar elemental compositions at standoff distances based on differences in key intensity ratios, further work is needed to reduce the number of false positives/negatives by refining the PLS-DA model to include a sufficient range of material classes and carefully selecting a detection threshold. In addition, we have demonstrated that LIBS can distinguish five different organophosphate nerve agent simulants at 20 meters, despite their similar stoichiometric formulas. Finally, a combined PLS-DA model for chemical, biological, and explosives detection using a single ST-LIBS sensor has been developed in order to demonstrate the potential of standoff LIBS for universal hazardous materials detection.

Double-pulse standoff laser-induced breakdown spectroscopy for versatile hazardous materials detection

We have developed a double-pulse standoff laser-induced breakdown spectroscopy (ST-LIBS) system capable of detecting a variety of hazardous materials at tens of meters. The use of a double-pulse laser improves the sensitivity and selectivity of ST-LIBS, especially for the detection of energetic materials. In addition to various metallic and plastic materials, the system has been used to detect bulk explosives RDX and Composition-B, explosive residues, biological species such as the anthrax surrogate Bacillus subtilis, and chemical warfare simulants at 20 m. We have also demonstrated the discrimination of explosive residues from various interferents on an aluminum substrate.

F-30 Improvement in Detection of Trace Hazardous Materials for Rohs Directive Using a High Efficiency Silicon Drift Detector

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Detection of explosive substances by tomographic inspection using neutron and gamma-ray spectroscopy

In recent years the detection and identification of hazardous materials has become increasingly important. This work discusses research and development of a technique which is capable of detecting and imaging hidden explosives. It is proposed to utilise neutron interrogation of the substances under investigation facilitating the detection of emitted gamma radiation and scattered neutrons. Pulsed fast neutron techniques are attractive because they can be used to determine the concentrations of the light elements (hydrogen, carbon, nitrogen, and oxygen) which can be the primary components of explosive materials. Using segmented High Purity Ge (HPGe) detectors and digital pulse processing [R.J. Cooper, G. Turk, A.J. Boston, H.C. Boston, J.R. Cresswell, A.R. Mather, P.J. Nolan, C.J. Hall, I. Lazarus, J. Simpson, A. Berry, T. Beveridge, J. Gillam, R.A. Lewis, in: Proceedings of the 7th International Conference on Position Sensitive Detectors, Nuclear Instruments and Methods A, in press; I. Lazarus, D.E. Appelbe, A. J. Boston, P.J. Coleman-Smith, J.R. Cresswell, M. Descovich, S.A.A. Gros, M. Lauer, J. Norman, C.J. Pearson, V.F.E. Pucknell, J.A. Sampson, G. Turk, J.J. Valiente-Dobón, IEEE Trans. Nucl. Sci., 51 (2004) 1353; R.J. Cooper, A.J. Boston, H.C. Boston, J.R. Cresswell, A.N. Grint, A.R. Mather, P.J. Nolan, D.P. Scraggs, G. Turk, C.J. Hall, I. Lazarus, A. Berry, T. Beveridge, J. Gillam, R.A. Lewis, in: Proceedings of the 11th International Symposium on Radiation Measurements and Application, 2006. [1–3]] the scatter path of incident photons can be reconstructed to determine the origin of the gamma-rays without the need for mechanical collimation by applying the Compton camera principle [V. Schonfelder, A. Hirner, K. Schneider, Nucl. Instr. and Meth. 107 (1973) 385; R.W. Todd, J.M. Nightingale, D.B. Everett, Nature 251 (1974) 132. [4,5]]. In addition, it is proposed to utilise the scattered neutrons which recoil from the materials being assayed, detecting them with a fast neutron detector providing data for inversion to tomographic images.In this paper, we present our approach to the design and implementation of a system for the efficient screening of goods in luggage and cargo containers. The simulation in a Monte Carlo framework using GEANT4 has been carried out for the imaging of gamma-ray events using the Compton camera design which will be discussed. The results of Compton camera measurements using HPGe detectors and the subsequent reconstructed images will also be presented.

Laser-induced breakdown spectroscopy (LIBS): a promising versatile chemical sensor technology for hazardous material detection

A series of laboratory experiments have been performed highlighting the potential of laser-induced breakdown spectroscopy (LIBS) as a versatile sensor for the detection of terrorist threats. LIBS has multiple attributes that provide the promise of unprecedented performance for hazardous material detection and identification. These include: 1) real-time analysis, 2) high sensitivity, 3) no sample preparation, and 4) the ability to detect all elements and virtually all hazards, both molecular and biological. We have used LIBS to interrogate a variety of different target samples, including explosives, chemical warfare simulants, biological agent simulants, and landmine casings. We have used the acquired spectra to demonstrate discrimination between different chemical warfare simulants, including those on soil backgrounds. A linear correlation technique permits discrimination between an anthrax surrogate and several other biomaterials such as molds and pollens. We also use broadband LIBS to identify landmine casings versus other plastics and environmental clutter materials. A new man-portable LIBS system developed as a collaborative effort between the U.S. Army Research Laboratory and Ocean Optics, Inc., is described and several other schemes for implementing LIBS sensors for homeland security and force protection are discussed.

PRIORITIZING OF ISSUES IN SCIENCE AND TECHNOLOGY POLICY FOR A SAFE AND SECURE SOCIETY

We have introduced prioritizing of issues in science and technology for a safe and secure society conducted by Study Group on Science and Technology Policy for a Safe and Secure Society of MEXT. Risks and threats have been collected and classified from various sources. Among the collected risks and threats, 17 areas including crime, terrorism, disaster, and infectious disease have been selected. Based on criteria for prioritizing issues, 35 priority issues (technologies for detection of hazardous materials, disaster mitigation, protection from infectious diseases, etc.) and eight common priority issues (simulation technologies for damage evaluation, sensor technologies, etc.) have been selected. Language: ja

Bananas, Explosives and the Future of Cavity Ring-Down Spectroscopy

Cavity ring-down spectroscopy has the potential to revolutionize environmental and agricultural monitoring, industrial process control and the detection and identification of hazardous materials.