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https://www.readbyqxmd.com/read/29881468/a-new-wipe-sampling-instrument-for-measuring-the-collection-efficiency-of-trace-explosives-residues
#1
Elizabeth L Robinson, Edward Sisco, Matthew E Staymates, Jeffrey A Lawrence
Trace explosives detection, a crucial component of many security screening environments, commonly employs wipe-sampling. Since collection of an explosive residue is necessary for detection, it is important to have a thorough understanding of the parameters that affect the efficiency of collection. Current wipe-sampling evaluation techniques for explosive particles have their limits: manual sampling (with fingers or a wand) is limited in its ability to isolate a single parameter and the TL-slip/peel tester is limited to a linear sample path...
January 14, 2018: Analytical Methods: Advancing Methods and Applications
https://www.readbyqxmd.com/read/29848336/identification-of-reaction-organization-patterns-that-naturally-cluster-enzymatic-transformations
#2
Carlos Vazquez-Hernandez, Antonio Loza, Esteban Peguero-Sanchez, Lorenzo Segovia, Rosa-Maria Gutierrez-Rios
BACKGROUND: Metabolic reactions are chemical transformations commonly catalyzed by enzymes. In recent years, the explosion of genomic data and individual experimental characterizations have contributed to the construction of databases and methodologies for the analysis of metabolic networks. Some methodologies based on graph theory organize compound networks into metabolic functional categories without preserving biochemical pathways. Other methods based on chemical group exchange and atom flow trace the conversion of substrates into products in detail, which is useful for inferring metabolic pathways...
May 30, 2018: BMC Systems Biology
https://www.readbyqxmd.com/read/29797696/rapid-quantitative-analysis-of-multiple-explosive-compound-classes-on-a-single-instrument-via-flow-injection-analysis-tandem-mass-spectrometry
#3
Alla Ostrinskaya, Roderick R Kunz, Michelle Clark, Richard P Kingsborough, Ta-Hsuan Ong, Sandra Deneault
A flow-injection analysis tandem mass spectrometry (FIA MSMS) method was developed for rapid quantitative analysis of 10 different inorganic and organic explosives. Performance is optimized by tailoring the ionization method (APCI/ESI), de-clustering potentials, and collision energies for each specific analyte. In doing so, a single instrument can be used to detect urea nitrate, potassium chlorate, 2,4,6-trinitrotoluene, 2,4,6-trinitrophenylmethylnitramine, triacetone triperoxide, hexamethylene triperoxide diamine, pentaerythritol tetranitrate, 1,3,5-trinitroperhydro-1,3,5-triazine, nitroglycerin, and octohy-dro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine with sensitivities all in the picogram per milliliter range...
May 24, 2018: Journal of Forensic Sciences
https://www.readbyqxmd.com/read/29784780/early-fossil-record-of-euarthropoda-and-the-cambrian-explosion
#4
Allison C Daley, Jonathan B Antcliffe, Harriet B Drage, Stephen Pates
Euarthropoda is one of the best-preserved fossil animal groups and has been the most diverse animal phylum for over 500 million years. Fossil Konservat-Lagerstätten, such as Burgess Shale-type deposits (BSTs), show the evolution of the euarthropod stem lineage during the Cambrian from 518 million years ago (Ma). The stem lineage includes nonbiomineralized groups, such as Radiodonta (e.g., Anomalocaris ) that provide insight into the step-by-step construction of euarthropod morphology, including the exoskeleton, biramous limbs, segmentation, and cephalic structures...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29762499/a-high-aspect-ratio-bifurcated-128-microchannel-microfluidic-device-for-environmental-monitoring-of-explosives
#5
Paul T Charles, Varun Wadhwa, Amara Kouyate, Kelly J Mesa-Donado, Andre A Adams, Jeffrey R Deschamps, Anne W Kusterbeck
Design and evolution of explosives monitoring and detection platforms to address the challenges of trace level chemical identification have led investigations into the use of intricately designed microfluidic devices. Microfluidic devices are unique tools that possess distinct characteristics that, when designed properly and configured with optical and fluidic components, can produce detection platforms with unmatched performance levels. Herein, we report the design, fabrication and integration of a bifurcated high aspect ratio microfluidic device containing 128 microchannels (40 mm × 40 μm × 250 μm; L × W × H) for explosives detection at trace levels...
May 15, 2018: Sensors
https://www.readbyqxmd.com/read/29756917/hyperfine-structure-induced-depolarization-of-impulsively-aligned-i_-2-molecules
#6
Esben F Thomas, Anders A Søndergaard, Benjamin Shepperson, Niels E Henriksen, Henrik Stapelfeldt
A moderately intense 450 fs laser pulse is used to create rotational wave packets in gas phase I_{2} molecules. The ensuing time-dependent alignment, measured by Coulomb explosion imaging with a delayed probe pulse, exhibits the characteristic revival structures expected for rotational wave packets but also a complex nonperiodic substructure and decreasing mean alignment not observed before. A quantum mechanical model attributes the phenomena to coupling between the rotational angular momenta and the nuclear spins through the electric quadrupole interaction...
April 20, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29739925/re-visiting-the-evolution-dispersal-and-epidemiology-of-zika-virus-in-asia
#7
John H-O Pettersson, Jon Bohlin, Myrielle Dupont-Rouzeyrol, Ola B Brynildsrud, Kristian Alfsnes, Van-Mai Cao-Lormeau, Michael W Gaunt, Andrew K Falconar, Xavier de Lamballerie, Vegard Eldholm, Didier Musso, Ernest A Gould
Based on serological evidence and viral isolation, Zika virus (ZIKV) has circulated for many years relatively benignly in a sylvatic cycle in Africa and an urban cycle in South East Asia (SEA). With the recent availability of limited but novel Indian ZIKV sequences to add to the plethora of SEA sequences, we traced the phylogenetic history and spatio-temporal dispersal pattern of ZIKV in Asia prior to its explosive emergence in the Pacific region and the Americas. These analyses demonstrated that the introduction and dispersal of ZIKV on the Pacific islands were preceded by an extended period of relatively silent transmission in SEA, enabling the virus to expand geographically and evolve adaptively before its unanticipated introduction to immunologically naive populations on the Pacific islands and in the Americas...
May 9, 2018: Emerging Microbes & Infections
https://www.readbyqxmd.com/read/29714302/ders-substrate-based-on-ners-sers-interaction-in-integrated-microfluidic-detection
#8
Cheng Xiao, Zhibin Chen, Mengze Qin, Dongxiao Zhang, Lei Fan
The systematic simulation study of a structure with nanogap-enhanced Raman scattering and surface-enhanced Raman scattering (NERS-SERS) substrate is presented. This double-enhanced Raman scattering (DERS) substrate with coupling between the localized surface plasmons of noble metal nanosphere colloids and surface plasmon polaritons of a 1D sinusoidal noble metal nanograting is analyzed. With the excitation light wavelength at 785 nm, the key structure parameters of noble metal nanospheres and sinusoidal noble metal nanogratings are deduced by FDTD...
April 20, 2018: Applied Optics
https://www.readbyqxmd.com/read/29674066/simple-multispectral-imaging-approach-for-determining-the-transfer-of-explosive-residues-in-consecutive-fingerprints
#9
Heidi Lees, Félix Zapata, Merike Vaher, Carmen García-Ruiz
This novel investigation focused on studying the transfer of explosive residues (TNT, HMTD, PETN, ANFO, dynamite, black powder, NH4 NO3 , KNO3 , NaClO3 ) in ten consecutive fingerprints to two different surfaces - cotton fabric and polycarbonate plastic - by using multispectral imaging (MSI). Imaging was performed employing a reflex camera in a purpose-built photo studio. Images were processed in MATLAB to select the most discriminating frame - the one that provided the sharpest contrast between the explosive and the material in the red-green-blue (RGB) visible region...
July 1, 2018: Talanta
https://www.readbyqxmd.com/read/29671188/state-firearm-laws-and-interstate-transfer-of-guns-in-the-usa-2006-2016
#10
Tessa Collins, Rachael Greenberg, Michael Siegel, Ziming Xuan, Emily F Rothman, Shea W Cronin, David Hemenway
In a cross-sectional, panel study, we examined the relationship between state firearm laws and the extent of interstate transfer of guns, as measured by the percentage of crime guns recovered in a state and traced to an in-state source (as opposed to guns recovered in a state and traced to an out-of-state source). We used 2006-2016 data on state firearm laws obtained from a search of selected state statutes and 2006-2016 crime gun trace data from the Bureau of Alcohol, Tobacco, Firearms, and Explosives. We examined the relationship between state firearm laws and interstate transfer of guns using annual data from all 50 states during the period 2006-2016 and employing a two-way fixed effects model...
June 2018: Journal of Urban Health: Bulletin of the New York Academy of Medicine
https://www.readbyqxmd.com/read/29664070/recent-advances-in-ambient-mass-spectrometry-of-trace-explosives
#11
REVIEW
Thomas P Forbes, Edward Sisco
Ambient mass spectrometry has evolved rapidly over the past decade, yielding a plethora of platforms and demonstrating scientific advancements across a range of fields from biological imaging to rapid quality control. These techniques have enabled real-time detection of target analytes in an open environment with no sample preparation and can be coupled to any mass analyzer with an atmospheric pressure interface; capabilities of clear interest to the defense, customs and border control, transportation security, and forensic science communities...
April 30, 2018: Analyst
https://www.readbyqxmd.com/read/29629760/use-of-rapid-reduced-electric-field-switching-to-enhance-compound-specificity-for-proton-transfer-reaction-mass-spectrometry
#12
Ramón González-Méndez, Peter Watts, D Fraser Reich, Stephen J Mullock, Stuart Cairns, Peter Hickey, Matthew Brookes, Chris A Mayhew
The high sensitivity of proton transfer reaction-mass spectrometry (PTR-MS) makes it a suitable analytical tool for detecting trace compounds. Its specificity is primarily determined by the accuracy of identifying the m/ z of the product ions specific to a particular compound. However, specificity can be enhanced by changing the product ions (concentrations and types) through modifying the reduced electric field. For current PTR-MS systems, this is not possible for trace compounds that would only be present in the reaction chamber of a PTR-MS for a short time (seconds)...
May 1, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29627997/sulfidic-anion-concentrations-on-early-earth-for-surficial-origins-of-life-chemistry
#13
Sukrit Ranjan, Zoe R Todd, John D Sutherland, Dimitar D Sasselov
A key challenge in origin-of-life studies is understanding the environmental conditions on early Earth under which abiogenesis occurred. While some constraints do exist (e.g., zircon evidence for surface liquid water), relatively few constraints exist on the abundances of trace chemical species, which are relevant to assessing the plausibility and guiding the development of postulated prebiotic chemical pathways which depend on these species. In this work, we combine literature photochemistry models with simple equilibrium chemistry calculations to place constraints on the plausible range of concentrations of sulfidic anions (HS- , HSO3 - , SO3 2- ) available in surficial aquatic reservoirs on early Earth due to outgassing of SO2 and H2 S and their dissolution into small shallow surface water reservoirs like lakes...
April 8, 2018: Astrobiology
https://www.readbyqxmd.com/read/29561042/ultra-high-sensitivity-of-luminescent-zncr-2-o-4-nanoparticles-toward-nitroaromatic-explosives-sensing
#14
Debamalya Ghosh, Uma Dutta, Ariful Haque, Natalia E Mordvinova, Oleg I Lebedev, Kamalesh Pal, Arup Gayen, Md Motin Seikh, Partha Mahata
Here, we report the luminescence based sensing of trace amounts of nitroaromatic explosive organic compounds. The luminescence emission of nanosized spinel oxide ZnCr2O4 with high chemical and thermal stabilities has been used as a potential probe to detect such organic explosives. Low temperature solution combustion synthesized ZnCr2O4 oxide with an average particle size of ∼9 nm exhibits strong luminescence emission at 410 nm upon excitation at 260 nm in an aqueous suspension. The presence of nitroaromatics in ZnCr2O4 suspension dramatically suppresses the luminescence emission providing an opportunity to detect it quantitatively...
April 3, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29540817/sediment-disturbance-by-ediacaran-bulldozers-and-the-roots-of-the-cambrian-explosion
#15
Luis A Buatois, John Almond, M Gabriela Mángano, Sören Jensen, Gerard J B Germs
Trace fossils of sediment bulldozers are documented from terminal Ediacaran strata of the Nama Group in Namibia, where they occur in the Spitskop Member of the Urusis Formation (Schwarzrand Subgroup). They consist of unilobate to bilobate horizontal to subhorizontal trace fossils describing scribbles, circles and, more rarely, open spirals and meanders, and displaying an internal structure indicative of active fill. Their presence suggests that exploitation of the shallow infaunal ecospace by relatively large bilaterians was already well underway at the dawn of the Phanerozoic...
March 14, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29509659/coupling-p-n-field-effect-transistor-circuits-for-low-concentration-methane-gas-detection
#16
Xinyuan Zhou, Liping Yang, Yuzhi Bian, Xiang Ma, Ning Han, Yunfa Chen
Nowadays, the detection of low concentration combustible methane gas has attracted great concern. In this paper, a coupling p+n field effect transistor (FET) amplification circuit is designed to detect methane gas. By optimizing the load resistance ( RL ), the response to methane of the commercial MP-4 sensor can be magnified ~15 times using this coupling circuit. At the same time, it decreases the limit of detection (LOD) from several hundred ppm to ~10 ppm methane, with the apparent response of 7.0 ± 0.2 and voltage signal of 1...
March 6, 2018: Sensors
https://www.readbyqxmd.com/read/29452562/deciphering-the-sunshine-act-transparency-regulation-and-financial-conflicts-in-health-care
#17
Richard S Saver
The Physician Payments Sunshine Act ("Sunshine Act"), enacted to address financial conflicts in health care, is the first comprehensive federal legislation mandating public reporting of payments between drug companies, device manufacturers, and medicine. This article analyzes the Sunshine Act's uneven record, exploring how the law serves as an intriguing example of the uncertain case for transparency regulation in health care. The Sunshine Act's bumpy rollout demonstrates that commanding transparency through legislation can be arduous because of considerable implementation challenges...
November 2017: American Journal of Law & Medicine
https://www.readbyqxmd.com/read/29431838/fabrication-of-a-self-assembled-and-flexible-sers-nanosensor-for-explosive-detection-at-parts-per-quadrillion-levels-from-fingerprints
#18
Thakshila Liyanage, Ashur Rael, Sidney Shaffer, Shozaf Zaidi, John V Goodpaster, Rajesh Sardar
Apart from high sensitivity and selectivity of surface-enhanced Raman scattering (SERS)-based trace explosive detection, efficient sampling of explosive residue from real world surfaces is very important for homeland security applications. Herein, we demonstrate an entirely new SERS nanosensor fabrication approach. The SERS nanosensor was prepared by self-assembling chemically synthesized gold triangular nanoprisms (Au TNPs), which we show display strong electromagnetic field enhancements at the sharp tips and edges, onto a pressure-sensitive flexible adhesive film...
April 30, 2018: Analyst
https://www.readbyqxmd.com/read/29353810/development-and-validation-of-a-solid-phase-extraction-sample-cleanup-procedure-for-the-recovery-of-trace-levels-of-nitro-organic-explosives-in-soil
#19
Jennifer L Thomas, Christopher C Donnelly, Erin W Lloyd, Robert F Mothershead, Mark L Miller
An improved cleanup method has been developed for the recovery of trace levels of 12 nitro-organic explosives in soil, which is important not only for the forensic community, but also has environmental implications. A wide variety of explosives or explosive-related compounds were evaluated, including nitramines, nitrate esters, nitroaromatics, and a nitroalkane. Fortified soil samples were extracted with acetone, processed via solid phase extraction (SPE), and then analyzed by gas chromatography with electron capture detection...
March 2018: Forensic Science International
https://www.readbyqxmd.com/read/29310209/highly-fluorescent-sensing-of-nitroaromatic-explosives-in-aqueous-media-using-pyrene-linked-pbema-microspheres
#20
Hamza Turhan, Ece Tukenmez, Bunyamin Karagoz, Niyazi Bicak
Crosslinked 2-bromoethyl methacrylate polymer (PBEMA) was prepared in micro-spherical form (2-5µm) by precipitation polymerization methodology. The bromide substituent was substituted with an azide group, which was then coupled with 1-[(2-Propynyloxy)methyl]pyrene] via alkyne-azide click chemistry. The pyrene-linked microspheres showed an intense green-blue excimer emission with a maximum at 480nm, implying π-π stacking between the pyrene moieties on the microsphere surfaces. This fluorescence emission is extremely sensitive to the aromatic nitro compounds...
March 1, 2018: Talanta
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