Diethyl Ethylphosphonate Research Articles

Diethyl ethylphosphonate retardants disturbed the gut microbiome and metabolite SCFAs in vitro based on simulator of the human intestinal microbial ecosystem

Diethyl ethylphosphonate (DEEP) as a novel organophosphorus flame retardant received increasing attention and its structure was discovered. But there are currently insufficient studies on how DEEP exposure affects the gut microbiome. In this study, the effects of DEEP on the structure and function of the human gut microbiota were examined using the SHIME system. Results from high-throughput sequencing of the 16S rRNA gene show that the high dose DEEP exposure reduced the Shannon and Simpson index in the transverse and descending colon. The Bacillota had the highest proportion while the proportion of Proteobacteria gradually decreased at the phylum level. The abundance of Escherichia, Prevotella, and Bilophila at the genus level increased with increasing doses of DEEP exposure. On the contrary, the abundance of Megasphaera, Klebsiella, and Phascolarctobacterium decreased. The short-chain fatty acids had a significant shift. With increasing doses of DEEP exposure, the concentration of acetic acid and propionic acid increased, while the concentration of butyric acid reached the highest at the medium dose of exposure. In addition, Bilophila, Psychrobacter, Escherichia, and Nostoe showed strong beneficial associations with acetic and propionic acids under DEEP exposure. Phocaeicola, Agathobacter, Klebsiella, Megasphaera, Phascolarctobacterium, and Bacteroides were negatively association with acetic and propionic acids. In a word, the study verified that exposure to different doses of DEEP can cause changes in the composition of the gut microbiome and metabolite SCFAs, which provides ideas for the investigation of other potential hazards of DEEP on human beings.

Phosphonate-based supercapacitor electrolyte integrating the advantages of flame retardancy, extreme temperature adaptability, and anti-supergravity

Traditional acetonitrile-based organic electrolytes continue to dominate in carbon-based supercapacitors due to their high performance-to-price ratio. However, its flammability, low extreme temperature applicability, and unknown anti-supergravity limit its application in some special scenarios (e.g., space exploration). For the first time, an electrolyte system based on potassium hexafluorophosphate (KPF6) and diethyl ethylphosphonate (DEEP) as the electrolyte salt and solvent, respectively, was proposed. The KPF6/DEEP system combines excellent flame retardancy, high capacitance performance at high (60 °C) and low (-70 °C) temperatures, anti-supergravity (60 G), and an operating voltage of up to 3.0 V, resulting in a stable and high power energy output of up to 16 Wh kg−1 for carbon-based supercapacitors at −60 °C. These benefits are primarily attributed to the distinct physical properties of DEEP (e.g., flame retardancy, low freezing point, high boiling point, and high compatibility with KPF6). Such outstanding overall performance, which incorporates excellent flame retardancy, extreme temperature adaptability, anti-supergravity, and cycle stability (capacity retention > 95 % after 14,000 cycles), outperforms the traditional acetonitrile-based system, opening up a new option for power devices for some applications with extreme environmental demands.

Smoke suppressant and fire‐retardant polyurethane‐polyisocyanurate (PIR) foam

AbstractIn this study, the combinations of phosphorous‐containing fire retardants such as triethyl phosphate, oligomeric triethyl phosphate, diethyl ethyl phosphonate, diethyl hydroxymethyl phosphonate, ammonium polyphosphate, and smoke suppressant zinc borate were used as additives in order to produce non‐toxic smoke suppressant and fire‐retardant rigid polyurethane‐polyisocyanurate (PIR) foams. Flame height and smoke density of polyurethane‐polyisocyanurate foam decreased by incorporating different combinations of combustion modifiers in PIR formulations. The smoke suppressant was zinc borate. The combination of zinc borate with triethyl phosphate, oligomeric triethyl phosphate, and diethyl hydroxymethyl phosphonate resulted in a good synergy. The cone calorimeter analysis showed that the best combinations were zinc borate (10.1%) and triethyl phosphate (13.7%), or zinc borate (10.1%), triethyl phosphate (6.9%), and oligomeric triethyl phosphate (7%) and they decreased the burning and smoke formation rate of PIR foam. These combinations may be applied to produce fire‐retardant PIR foam in the industry.

A nonflammable diethyl ethylphosphonate-based electrolyte improved by synergistic effect of lithium difluoro(oxalato)borate and fluoroethylene carbonate

The vital physical and chemical properties of the lithium conducting salt, solvent/co-solvent and functional additive determine the overall properties and performance of the resulting electrolyte formulation. Explorations on right combinations of the carefully selected electrolyte components are expected to further balance the electrochemical and safety performances of chosen electrolyte formulations in given cell chemistries. In this study, a new nonaqueous aprotic electrolyte is designed by using lithium difluoro(oxalato)borate (LiODFB) as conducting salt, diethyl ethylphosphonate (DEEP) as solvent, and fluoroethylene carbonate (FEC) as co-solvent to achieve a nonflammable electrolyte formulation with competent electrochemical performance. The LiODFB and FEC are believed to take part in complex interfacial interactions with a synergistic effect. LiNi0.8Co0.1Mn0.1O2 (NCM811)‖Li cells using the optimized electrolyte formulation of 1.3 M LiODFB/DEEP 30% FEC exhibits a stable long-term cycling performance at 1.0 C with a reversible average specific discharge capacity of 169.5 mAh g−1 during 100 cycles, which is comparable to cells using commercial electrolytes. Furthermore, the 1.3 M LiODFB/DEEP 30% FEC electrolyte shows good thermal stability and effectively reduces the heat generation during thermal decomposition of NCM811 cathode. The results provide a good reference for the design of next generation of safe, nonflammable electrolytes for lithium-based battery application.

Organophosphorus flame retardants in children’s car seats: Implications for vehicle air quality

Flame retardants (FRs) are used in many consumer products for fire safety reasons. Their use in children’s car seats may result in children’s and vehicle occupants’ exposure to these compounds including inhalation exposure through poor vehicle air quality. We have tested several children’s car seats from local retailers for the presence of FRs. A number of organophosphorus flame retardants (OPFRs) were identified in the extracts (dichloromethane) of eight foam materials taken from the seats. They included several organophosphates (triethyl phosphate (TEP) (detected in all 8 samples) followed by tris(butoxyethyl) phosphate (2), triphenyl phosphate (1), di-(t-butylphenyl) phenyl phosphate (1) butyl diethyl phosphate (1) and tris(4-tert-butylphenyl) phosphate (1)) and organophosphonates (two isomers of 5-ethyl-2-methyl-2-oxido-1,3,2-dioxaphosphinan-5-yl)methyl methyl methylphosphonate (PMMMP) (detected in 5 of the 8 samples) followed by diethyl ethylphosphonate (1) and 4-methoxy-2-methylbutyl ethyl butylphosphonate (1)). TEP was the most frequently detected among these OPFRs. Due to its relatively high vapour pressure (0.39 mm Hg at 25 °C) among detected OPFRs, TEP is most likely to emit into vehicle interior air during product use, which could result in inhalation exposure for the children using the car seat and other passengers. We therefore have tested the emission rate of TEP in a micro-chamber at 40 °C for estimating potential exposure of vehicle occupants. The emission profile shows the concentrations of TEP in the chamber reached a maximum within the first few hours and then decreased over time. There was a lack of correlation between 24-hour average emission rate and concentrations of TEP in the product. The exact health risk to children and other vehicle occupants in this case requires further research to quantify.

Effect of expandable graphite and molybdenum trioxide in nitrogen/phosphorus synergistic system on acoustic performance and fire safety in rigid polyurethane foam

AbstractTo explore acoustic performance and flame retardancy of expandable graphite (EG) and molybdenum trioxide (MoO3) in rigid polyurethane foam (RPUF) with nitrogen/phosphorus synergistic system, ammonium polyphosphate (APP), diethyl ethylphosphonate (DEEP), EG, and MoO3 were employed in RPUF. Compared with flame‐retarded RPUFs, neat‐RPUF attained an open porosity value of 45.3%, which provided good tortuosity for wave propagation and acoustic attenuation, and therefore had the best performance in acoustic absorption. Although the addition of flame retardant sacrificed sound‐absorbing properties, the flame retardancy performance of foams were indeed significantly improved. The Limited Oxygen Index (LOI) value of RPUF with 70 php EG alone increased from 19.4% of Neat‐RPUF to 35.6%. Regarding to CO and CO2 emission, RPUF with 10 php MoO3, 30 php APP, and 30 php DEEP gained minimum value of average CO yield and average CO2 yield, which were 0.06 kg/kg and 0.78 kg/kg, respectively, ascribed to the accelerated formation of the compact carbon layers by MoO3.

Acoustic Performance and Flame Retardancy of Ammonium Polyphosphate/Diethyl Ethylphosphonate Rigid Polyurethane Foams.

Flame-retardant water-blown rigid polyurethane foams (RPUFs) modified by ammonium polyphosphate (APP) and diethyl ethylphosphonate (DEEP) were synthesized by a one-pot free-rising method. We performed scanning electron microscopy (SEM), compression strength tests, acoustic absorption measurements and thermogravimetric analysis, as well as limited oxygen index, vertical burning and cone calorimeter tests to investigate the mechanical properties, acoustic performance and flame retardancy of the foams. SEM confirmed that the open-cell structures of the foams were successfully constructed with the introduction of a cell-opening agent. Upon using 20 php APP, the average acoustic absorption coefficient of the foam reached 0.535 in an acoustic frequency range of 1500–5000 Hz. The results of thermogravimetric analysis demonstrated that the incorporation of APP and DEEP can effectively restrain mass loss of RPUFs during pyrolysis. In particular, the compressive strength of a foam composite containing 5 php APP and 15 php DEEP increased to 188.77 kPa and the LOI value reached 24.9%. In a vertical burning test and a cone calorimeter test, the joint use of APP and DEEP endowed RPUFs with a V-0 rating and they attained a THR value of 23.43 MJ/m2. Moreover, the addition of APP improved the acoustic absorption performance of the foam, verified by acoustic absorption measurements. Considering potential applications, the formulation containing 15 php APP and 5 php DEEP could be used in the preparation of a new flame-retardant acoustic absorption rigid polyurethane foam.

Adsorption of nerve agent simulants onto vermiculite structure: Experiments and modelling

Chemical warfare agents are still a threat to humanity despite the existence of a ban on their production and use. There are many new materials that have been experimentally verified to be effective in degrading and eliminating various chemical warfare agents; however, clay minerals still remain very effective, environmentally friendly and not expensive. Vermiculites modified with hexadecylpyridinium, hexadecyltrimethylammonium and tetramethylammonium cations were used for static sorption of vapours of two simulants of nerve agents: dimethyl methyl phosphonate and diethyl ethyl phosphonate. The materials before and after sorption were characterized using infrared spectroscopy, X-ray diffraction and carbon phase analysis. The breakthrough time and capture of simulants were measured using dynamic sorption test. Molecular modelling was used to confirm the experimental results and provide a deeper insight into the structure of the materials and sorption processes.

Anti-melanogenesis potential of a new series of Morita-Baylis-Hillman adducts in B16F10 melanoma cell line

Melanin is a natural polymer pigment which provides skin photoprotection against ultraviolet radiation. An excessive synthesis of melanin leads to hyperpigmentation disorders. Tyrosinase catalyzes the rate limiting steps on melanogenesis. Therefore, tyrosinase inhibitors have potential applications in medicine and cosmetic fields. We carried out herein the screening of a family of cyclic Morita-Baylis-Hillman adducts (MBH) to find out their effects on tyrosinase activity and on melanogenesis in murine melanoma B16F10 cell line. Kinetic analysis of tyrosinase inhibition showed that compounds 1a (2-hydroxymethyl) cyclohex-2-enone) and 3f (diethyl (1-(6-oxocyclohex-1-en-1-yl) ethyl-phosphonate) were competitive inhibitors, whereas the compound 2b (6-oxocyclohex-1-en-1-yl) ethyl acetate) was a non-competitive one. Additionally we have found that (1a, 2b and 3f) compounds had a strong melanogenesis inhibition effect in isobutylmethylxanthine (IBMX)-treated murine melanoma B16F10 cells when tested at low and non cytotoxic dose (10–50 µM), by attenuating the melanin production, intracellular tyrosinase activity and tyrosinase expression. Thus, we suggest that these compounds could be used as effective skin-whitening agents.

Review—Ink-Jet Printed Wireless Liquid and Gas Sensors for IoT, SmartAg and Smart City Applications

The manuscript explores the process of integrating chemical and substance (liquid or gas) detecting sensors into the Internet of Things (IoT). Focusing on recently developed sensors that are integrated into wireless platforms, a microfluidic sensor and its mechanism to detect different types of liquids are illustrated before examining gas sensors that can detect the presence of targeted gases in very small amounts; 2.5 ppm (parts per million) for dimethyl methyl phosphonate (DMMP), 2.0 ppm for diethyl ethyl phosphonate (DEEP) and 10 ppm for ammonia (NH3). Finally, four Radio Frequency Identification platforms embedded with sensors are mentioned showing how they transmit info through frequency tuning.

Sensitivity enhancement of flexible gas sensors via conversion of inkjet-printed silver electrodes into porous gold counterparts

This work describes a facile, mild and general wet chemical method to change the material and the geometry of inkjet-printed interdigitated electrodes (IDEs) thus drastically enhancing the sensitivity of chemiresistive sensors. A novel layer-by-layer chemical method was developed and used to uniformly deposit semiconducting single-wall carbon nanotube (SWCNT)-based sensing elements on a Kapton® substrate. Flexible chemiresistive sensors were then fabricated by inkjet-printing fine-featured silver IDEs on top of the sensing elements. A mild and facile two-step process was employed to convert the inkjet-printed dense silver IDEs into their highly porous gold counterparts under ambient conditions without losing the IDE-substrate adhesion. A proof-of-concept gas sensor equipped with the resulting porous gold IDEs featured a sensitivity to diethyl ethylphosphonate (DEEP, a simulant of the nerve agent sarin) of at least 5 times higher than a similar sensor equipped with the original dense silver IDEs, which suggested that the electrode material and/or the Schottky contacts between the electrodes and the SWCNTs might have played an important role in the gas sensing process.

Kinetic of the gas-phase reactions of OH radicals and Cl atoms with diethyl ethylphosphonate and triethyl phosphate

Abstract In this paper, the relative-rate technique has been used to obtain rate coefficients for the reaction of two organophosphorus compounds: Triethyl phosphate (TEP) and Diethyl ethylphosphonate (DEEP) with OH radicals and Cl atoms at atmospheric pressure and at different temperatures. The calculated rate constants were fitted to the Arrhenius expression over the temperature range 298–352 K. The following expressions (in cm3 molecule−1 s−1) were obtained for the reactions of OH and CL with DEEP and TEP: kOH+DEEP = (7.84 ± 0.65) × 10−14exp((1866 ± 824)/T), kOH+TEP = (6.54 ± 0.42) × 10−14exp((1897 ± 626)/T), kCl+DEEP = (5.27 ± 0.80) × 10−11exp(765 ± 140/T) and kCl+TEP = (5.23 ± 0.80) × 10−11exp(736 ± 110/T). These results show that the reaction of the studied compounds with Cl atoms proceeds more rapidly than that with OH radicals. The related tropospheric lifetimes suggest that once emitted into the atmosphere, TEP and DEEP can be removed within a few hours in areas close to their emission sources. TEP and DEEP are principally removed by OH radicals. However, in coastal areas where the Cl atoms’ concentration is higher, TEP and DEEP removal by reaction with Cl atoms could be a competitive process.

Preparation and characterization of flame retardant phase change materials by microencapsulated paraffin and diethyl ethylphosphonate with poly(methacrylic acid‐co‐ethyl methacrylate) shell

ABSTRACTMicrocapsules containing paraffin and diethyl ethylphosphonate (DEEP) flame retardant with uncrosslinked and crosslinked poly (methacrylic acid‐co‐ethyl methacrylate) (P(MAA‐co‐EMA)) shell were fabricated by suspension‐like polymerization. The surface morphologies of the microencapsulated phase change materials (microPCMs) were studied by scanning electron microscopy. The thermal properties and thermal stabilities of the microPCMs were investigated by differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The flame retarding performances of the microcapsule‐treated foams were calculated by using an oxygen index instrument. The DSC results showed that the crosslinking of the polymer shell led to an increase in the melting enthalpies of the microcapsule by more than 15%. The crosslinked P(MAA‐co‐EMA) microcapsules with DEEP and without DEEP have melting enthalpies of 67.2 and 102.9 J/g, respectively. The TGA results indicated that the thermal resistant temperature of the crosslinked microcapsules with DEEP was up to 171°C, which was higher than that of its uncrosslinked counterpart by ∼20°C. The incorporation of DEEP into the microPCM increased the limiting oxygen index value of the microcapsule‐treated foams by over 5%. Thermal images showed that both microcapsule‐treated foams with and without DEEP possessed favorably temperature‐regulated properties. As a result, the microPCMs with paraffin and DEEP as core and P(MAA‐co‐EMA) as shell have good thermal energy storage and thermal regulation potentials, such as thermal‐regulated foams heat insulation materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41880.

Real-time detection of chemical warfare agent simulants in forensic samples using active capillary plasma ionization with benchtop and field-deployable mass spectrometers

A novel analytical technique to detect chemical warfare agent (CWA) simulants in forensic samples is presented. Three G-agent type simulants that closely mimic real CWAs, namely dimethyl methylphosphonate (DMMP), diethyl ethylphosphonate (DEEP), and diethyl phosphoramidate (DEPA), and in addition a hydrolysis product, pinacolyl methylphosphonate (PMP), were utilized. Dilute solutions spotted onto six different forensic matrices were used to evaluate the capability of an active capillary plasma ionization source, which could be attached to the inlets of either a conventional benchtop ion trap mass spectrometer or a miniaturized ion trap mass spectrometer, under ambient conditions. The sample solutions and matrix surfaces were exposed for about 10–20 seconds at a distance of 1 cm from the plasma ion source inlet. This real-time methodology was found to have a shorter analysis time than previously reported techniques. A full method validation, quantitative studies, and optimization for detection of real CWAs on forensic matrices should be done in the future.

Synergistic effect of expandable graphite, diethyl ethylphosphonate and organically-modified layered double hydroxide on flame retardancy and fire behavior of polyisocyanurate-polyurethane foam nanocomposite

Abstract Halogen-free flame-retarded rosin-based rigid PIR foam nanocomposites have been successfully prepared by in-situ polymerization, which were based on renewable rosin polyester polyol, halogen-free flame retardants (such as expandable graphite and diethyl ethylphosphonate) and organically-modified nanoclay (such as organically-modified montmorillonite or organically-modified layered double hydroxide). The morphology, thermal conductivity, mechanical property, thermal stability, flame retardancy and fire behavior of PIR foam nanocomposites were comprehensively investigated. Furthermore, potential synergistic effect between organically-modified nanoclay and flame retardants on improving the flame retardancy and fire behavior of rosin-based rigid PIR foam has been investigated in detail. X-ray diffraction and transmission electron microscopy studies confirmed that exfoliated structure of OMMT or OLDH in PIR-FR45-OMMT2.0 or PIR-FR45-OLDH3.0 nanocomposite. The flammability and compressive strength tests showed that PIR-FR45-OMMT2.0 and PIR-FR45-OLDH3.0 nanocomposites possessed significantly improved flame retardancy and slightly enhanced mechanical property compared with neat PIR foam. At the same time, PIR-FR45-OMMT2.0 and PIR-FR45-OLDH3.0 nanocomposites possessed relatively low thermal conductivity, which can meet requirement of engineering applications as insulating material. Furthermore, commonly OMMT showed no synergistic effect with flame retardants when dealing with fire behavior. However, OLDH showed synergistic effect with flame retardants on improving the flame retardancy and fire behavior of rosin-based rigid PIR foam. The reason is that OLDH can promote the formation of reinforced char layer, provide an effective barrier against heat and oxygen, release noncombustible gases, and simultaneously effectively suppress smoke and gases during the combustion process.

Understanding the interactions of phosphonate-based flame-retarding additives with graphitic anode for lithium ion batteries

The compatibility with graphitic anode has been one key problem in developing flame-retarding additives for lithium ion batteries. To understand the interactions between flame-retarding additives and graphitic anode, two phosphonate esters (dimethyl methylphosphonate DMMP and diethyl ethylphosphonate DEEP) are selected and characterized as flame retardant addtives. DEEP is reported as a flame-retarding additive for the first time. Their interactions with graphite anode are characterized via current-static charge–discharge, ex-situ XRD, FE-SEM and AC impedance. The results reveal that the two phosphonate esters demonstrate different reaction mechanisms with graphitic anode, which result in different anode compatibility. These findings may be useful for designing better flame-retarding additives for lithium ion batteries.

A nanocomposite of copper(ii) functionalized graphene and application for sensing sulfurated organophosphorus pesticides

Reduced graphene oxide is modified with sulfanilic acid diazonium salt followed by copper(II) chelating to form a Cu complex nanocomposite. Characterization by Raman spectroscopy, FTIR and EDS, XPS, cyclic voltammetry demonstrates the successful functionalization of the graphene surfaces. Electrodes that are prepared by drop-casting the suspended nanocomposite solution on interdigitated electrodes (IDE) are tested for a novel pulsed amperometric detection of a series of sulfurated organophosphorus (SOP) pesticides, parathion, fenitrothion and malathion. A linear relationship of the pulsed amperometric current to the logarithmic value of concentration of the three SOPs is demonstrated with a R2 value of ∼0.95 at the S-OP concentration range of 1 ppb to 104 ppb. Negligible amperometric currents are observed in the control experiments using diethyl ethylphosphonate (DEEP) and dimethyl methyl phosphonate (DMMP), or S2−, SO32−, SO42− ions, suggesting sensing specificity to sulfurated compounds.

Dust as a collection media for contaminant source attribution

Dust was investigated for its ability to retain source attribution profiles (SAPs) after chemical exposure. Three distinct sources of the organophosphate pesticide acephate were investigated as a proof-of-concept model. In addition, attribution profiles were created and tested using compounds related to chemical warfare agents (CWAs), specifically VX and G-series agents: O-ethyl methylphosphonothioate (EMPTA), N,N-diisopropylmethylamine (DIPMA), N,N-diisopropylethylamine (DIEA), diisopropylamine (DIPA), diethyl aniline (DEA), diethyl ethyl phosphonate (DEEP), trimethyl phosphite (TMP), dimethyl hydrogen phosphite (DMHP), diethyl hydrogen phosphite (DEHP), triethyl phosphate (TEP), ethyl methylphosphonate (EMPA), and diisopropyl methylphosphonate (DIMP). Dust was collected from a storage shed, aliquots deposited on carpet and loaded with distinct chemical profiles using an exposure chamber and aerosolizer. After a given period of time (1h, 24h, or 72 h), the dust was extracted and its SAP analyzed by gas chromatography-mass spectrometry (GC-MS) and/or liquid chromatography-tandem mass spectrometry (LC-MS/MS). Principal components analysis (PCA) was used to determine the association of dust exposed to the same and different chemical sources. PCA results demonstrate that dust samples exposed to distinct chemical sources are clearly differentiated from one another across all collection times. Furthermore, dust aliquots exposed to the same source can be clearly associated with one another across all collection times. When the CWA-related compounds were subjected to elevated temperature (90°C) conditions, it was found that the signature was stable at the 1h and 24h collections. At 72 h and elevated temperature, larger deviations from the control were observed for some compounds. Elevated pH (10) affected the profile to a lesser degree than elevated temperature. Overall, dust is found to be an effective media for the in situ collection of source attribution profiles.

Rate Constants for the Gas-Phase Reactions of OH Radicals with Dimethyl Phosphonate over the Temperature Range of 278−351 K and for a Series of Other Organophosphorus Compounds at ∼280 K

Rate constants for the gas-phase reactions of OH radicals with dimethyl phosphonate [DMHP; (CH3O)2P(O)H] were measured over the temperature range of 278-351 K at atmospheric pressure of air using a relative rate method with 4-methyl-2-pentanone as the reference compound. The Arrhenius expression obtained was 1.01 x 10(-12) e((474 +/- 159)/T) cm(3) molecule(-1) s(-1), where the indicated error is two least-squares standard deviations and does not include uncertainties in the rate constants for the reference compound. Rate constants for the gas-phase reactions of OH radicals with dimethyl methylphosphonate [DMMP, (CH3O)2P(O)CH3], dimethyl ethylphosphonate [DMEP, (CH3O)2P(O)C2H5], diethyl methylphosphonate [DEMP, (C2H5O)2P(O)CH3], diethyl ethylphosphonate [DEEP, (C2H5O)2P(O)C2H5], and triethyl phosphate [TEP, (C2H5O)3PO] were also measured at 278 and/or 283 K for comparison with a previous study (Aschmann, S. M.; Long, W. D.; Atkinson, R. J. Phys. Chem. A, 2006, 110, 7393). With the experimental procedures employed, experiments conducted at temperatures below the dew point where a water film was present on the outside of the Teflon reaction chamber resulted in measured rate constants which were significantly higher than those expected from the extrapolation of rate data obtained at temperatures (283-348 K) above the dew point. Using rate constants measured at > or = 283 K, the resulting Arrhenius expressions (in cm(3) molecule(-1) s(-1) units) are 6.25 x 10(-14) e((1538 +/- 112)/T) for DMMP (283-348 K), 9.03 x 10(-14) e((1539 +/- 27)/T) for DMEP (283-348 K), 4.35 x 10(-13) e((1444 +/- 148)/T) for DEMP (283-348 K), 4.08 x 10(-13) e((1485 +/- 328)/T) for DEEP (283-348 K), and 4.07 x 10(-13) e((1448 +/- 145)/T) for TEP (283-347 K), where the indicated errors are as above. Aerosol formation at 296 +/- 2 K from the reactions of OH radicals with these organophosphorus compounds was relatively minor, with aerosol yields of < or = 8% in all cases.

Detection of G-Type Nerve Agent Simulants Based on a Double Reflection DBR Porous Silicon Interferometer

Distributed Bragg re ector (DBR) porous silicon (PSi) chips with two re ection peaks were fabricated by electrochemical etching in an aqueous ethanolic HF solution and were used to detect of chemical nerve agent simulants. Dimethyl methylphosphonate (DMMP) is a simulant for G-type nerve agents. The manufactured DBR PSi chips exhibit two sharp photonic bands, 560 and 717 nm, with narrow full widths at half maximum (FWHM) of 15 and 20 nm, respectively. The detection method involved the shift of the DBR re ection peaks in the re ectivity spectra under exposure to vapors of the analyte. Rapid detection was achieved in few seconds in situ and the observed red shift of the DBR peaks resulted from an increase in the refractive indices in DBR PSi. When the DBR PSi chips were exposed to vapor of DMMP, the two re ection peaks from DBR PSi were red-shifted by 22 and 32 nm, respectively. Real-time detection for the stimulant indicated that the detection measurements were reversible. Detection of other analytes, such as triethyl phosphate (TEP) and diethyl ethylphosphonate (DEEP), has been also achieved.