Search NASA⌕ Search

SEARCH · Search NASA

Results for “additional protocol”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Field Implementation of Nuclear Safeguards: ENEA' s Capability Projection - 17174

The Non-Proliferation Treaty (NPT) for Italy entered into force on May 2, 1975, in the framework of the national political position to deal with the nuclear energy only for civilian medical and industrial uses, being the country included in the NNWS (Non-Nuclear Weapon States). It is recognized that for these scopes nuclear material is produced, used, shipped and disposed, but it is at the same time known that it is not like any other material. The signature of further international treaties like the Additional Protocol to NPT led the Italian Ministry for the Economic Development (MISE) to take advantage of the public Italian Agency for Energy Environment and the Economic Development (ENEA) by means of a three years basis renewable agreement that could support the Ministry in fulfilling the clauses and obligations rising from the treaty itself and then fostering R and D in the field of the safeguards. MISE supported the procurement of a mobile laboratory able to bring sophisticated analysis instruments on the field in case of suspected environmental contamination deriving from the presence of nuclear materials. The description of this mobile laboratory and its capabilities is illustrated in this paper. (authors)

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2019

Microstructural Characterization of Alloy 709 Plate Materials with Additional Heat Treatment Protocol

This report provides the results on microstructural characterization of the first commercial heat of Alloy 709 plate material which has undergone additional heat treatment protocol. The report is a Level 4 deliverable in FY19 (M4AT-19AN020502012), under the Work Package AT19AN0205201, “A709 Development – ANL.” The study involves thermodynamic-kinetic modeling, heat treating of materials, microhardness testing, x-ray diffraction (XRD) study, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) study. Through thermodynamic-kinetic modeling, it is determined that after an 1100°C solutionizing treatment, heat treating of Alloy 709 at 775°C for 10 hours or at 900°C for 10 hours are candidate recipes for promoting desired microstructural features. Both heat treatments were executed on small samples of the AOD-1100°C condition of the commercial heat of Alloy 709. Micro-hardness tests showed that both treatments increases the hardness of the material. XRD showed that both treatments brings out M23C6 and MX phases, though the 775°C/10h-treatment has more profound effect. The TEM study revealed that similar for both conditions, M23C6 precipitated on grain boundaries and within grain interior. In contrast, after the 775°C/10h treatment, the dislocations are decorated with MX nano particles, while after the 900°C/10h treatment, most of the dislocations are free of MX particles. It is thus determined that the 775°C/10h treatment has a better potential to provide enhanced creep properties by pinning the dislocations with nano particles. Following this study, the 775°C/10h treatment was carried out on a large ESR-1100°C plate at Idaho National Laboratory. Hardness testing and microstructural characterization were performed and compared between the two materials being heated treated under the same protocol. The implication on mechanical properties was briefly discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2023

ETF Grout Expansion: Evaluation of MgO Additions and Struvite Precipitation Protocol for Potential Expansion

The ETF ammonia tolerant grout waste form was developed by the Vitreous State Laboratory (VSL) to stabilize ammonium and thereby prevent emission of ammonia vapor during solidification of an ammonium-rich, concentrated sulfate aqueous waste stream generated at the Hanford Effluent Treatment Facility (ETF). VSL did not observe expansion in samples prepared during the waste form development work. However, Savannah River National Laboratory (SRNL) personnel did encounter expansion, in some cases up to 20+ volume percent expansion in ETF grout samples while preforming work scope to evaluate compositional ranges for ETF brine and of the precipitation and solidification reagent. The work requests can be found in Washington River Protection Services (WRPS) Statement of Work (SOW), Requisitions #: 339922 Revisions 0 and 1, March 11, 2021, and November 2021. Additional evaluation was requested by WRPS SOW Requisitions #: 356730, Revision 1, February 1, 2022, to determine whether differences in the slags or differences in sample preparation protocols used by VSL and SRNL were the cause of the expansion observed in the SRNL samples. G. Chen, WRPS, arranged a materials exchange between VSL and SRNL and coordinated the VSL protocol for grouting and curing 1L of Base Case ETF simulant. Materials were exchanged between VSL and SRNL and both laboratories performed the VSL struvite precipitation-solidification protocol and cured samples for at least 28 days. VSL and SRNL encountered expansion, at varying degrees, in all samples prepared under the material exchange and grouting protocol. Additional material exchange testing between VSL and SRNL and alternative materials evaluation to further investigate the causes of grout expansion and differentiate the effects of various dry materials, grouting procedures, and curing containers was requested by WRPS SOW Requisitions #: 356730, Revision 2, January 10, 2023. Pacific Northwest National Laboratory (PNNL) assembled and distributed materials to both laboratories for testing. Observations from this study indicated variations in MgO additions, water-to-dry mix (dm) ratios and curing containers did not correlate to ETF ammonia grout expansion. In comparison to previous work, SRNL observed the addition rate of NaOH to be a potential factor for the final pH in the struvite precipitation step. In the current testing NaOH was added in bulk (5-10 mL at one time) during the precipitation step. The resulting pH was 7.57-9.15 which is slightly higher than pH observed at a slower addition rate. Additional testing is needed to identify the presence and/or struvite stability in high-pH struvite precipitant ETF ammonia grout samples. Therefore, based on current data, it is unknown if NaOH addition rate is the fundamental cause of grout expansion.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Left ventricular ejection fraction determined with the simulation of a very low-dose CZT-SPECT protocol and an additional count-calibration on planar radionuclide angiographic data

Purpose: To determine whether the left ventricular ejection fractions (EFs), measured on a high-sensitivity CZT single photon emission computed tomography (SPECT)-camera with a 70% reduction in recording times and a prevention of EF overestimation through an additional count-calibration, are concordant with reference EF from planar radionuclide angiography (2D-RNA). Methods: An additional 10-minute CZT-SPECT recording was performed in patients referred to 2D-RNA for cardiomyopathy (n = 23) or chemotherapy monitoring (n = 50) with an in vivo red blood cell labeling with 850 MBq {sup 99m}TcO{sub 4}{sup −}. The EF, obtained from CZT-SPECT with 100% (SPECT100) or 30% (SPECT30) projection times and with a SPECT-count calibration on the 2D-RNA counts of corresponding cavity volumes, were compared to EF from 2D-RNA. Results: Strong and equivalent relationships were documented between the EF from 2D-RNA and the calibrated EF from SPECT100 (y = 0.89x + 6.62; R{sup 2} = 0.87) and SPECT30 (y = 0.87x + 8.40; R{sup 2} = 0.85), and the mean EF from SPECT100 (54% ± 15%) and SPECT30 (53% ± 16%) were close to that from 2D-RNA (55% ± 15%). However, upward shifts in these mean values were documented in the absence of count calibration for both SPECT100 (60% ± 18%) and SPECT30 (60% ± 18%). Conclusion: Left ventricular EF may be determined on a high-sensitivity CZT-camera, a 70% reduction in injected activities, and an additional count-calibration for further enhancing the concordance with 2D-RNA values. [French] French Abstract: Objectif: Déterminer si les fractions d'éjection ventriculaire gauche (EF) mesurées sur une caméra CZT SPECT à haute sensibilité avec une réduction de 70% des temps d'enregistrement et une prévention de la surestimation de l'EF grâce à un étalonnage supplémentaire des coups concordent avec les EF de référence obtenues par angiographie scintigraphique planaire (2D-RNA). Méthodes: Un enregistrement CZT-SPECT supplémentaire de 10 minutes a été réalisé chez les patients référés pour évaluation de cardiomyopathie (n=23) ou suivi de chimiothérapie (n = 50) par angiographie scintigraphique planaire (2D-RNA) au globules rouges marqués avec 850 MBq 99mTcO4-. Les EF, obtenues au moyen d’une caméra CZT-SPECT avec 100% (SPECT100) ou 30% (SPECT30) de temps d’acquisition et avec étalonnage des coups SPECT sur les images 2D-RNA des volumes de cavité correspondants ont été comparés aux EF à partir de 2D-RNA. Résultats: une corrélation significative existe entre les EF obtenues par 2D-RNA et les EF étalonnées obtenues par SPECT100 (y = 0,89x + 6,62; R2 = 0,87) et SPECT30 (y = 0,87x + 8,40; R2 = 0,85). Les EF moyennes de SPECT100 (54 ± 15%) et SPECT30 (53 ± 16%) sont similaires à celles obtenues par 2D-RNA (55 ± 15%). En l'absence d'étalonnage de comptage des études SPECT100 (60 ± 18%) et SPECT30 (60 ± 18%), ces valeurs moyennes d’EF sont généralement plus élevées. Conclusion: La fonction ventriculaire gauche peut être déterminée avec une caméra CZT à haute sensibilité, une réduction des activités injectées et un étalonnage supplémentaire des coups pour améliorer la concordance avec les valeurs obtenues par 2D-RNA. [Spanish] Spanish Abstract: Propósito: Determinar si la fracción de eyección del ventrículo izquierdo, medida con la cámara CZT-SPECT con una reducción del 70% en tiempo de grabación y con la prevención de la sobreestimación mediante una calibración de cuentas adicional, que sea concordante con el valor referencia de fracción de eyección mediante radiografía planar de radionucleidos. (2D-RNA). Métodos: Una grabación adicional de 10 minutos con CZT-SPECT se realizo en pacientes referidos a radiografía planar de radionucleidos (2D-RNA) por miocardiopatías. (n = 23) o para monitorizar las quimioterapias (n = 50) con marcaje de glóbulos rojos con 850 MBq 99m TcO4. La fracción de eyección obtenida por CZT-SPECT con 100% (SPECT100) o 30% (SPECT30) de tiempo de proyección, y con SPECT con calibración de cuentas con el 2D-RNA, los volúmenes de cavidades fueron comparados con fracción de eyección . Relaciones fuertes y equivalentes fueron documentados entre fracción de eyección del 2D-RNA, y la forma calibrada de la fracción de eyección SPECT100 (y = 0.89x + 6.62; R2 = 0.87) y SPECT30 y = 0.87x + 8.40; R2 = 0.85), y la media de fracción de eyección de SPECT100 (54 ± 15%) and SPECT30 (53 ± 16%) fueron cercanos a la de el 2D-RNA (55 ± 15%). Aunque, aumentos en estas medias se documentaron en la ausencia de la calibración de cuentas para SPECT100 (60 ± 18%) y SPECT30 (60 ± 18%). Conclusión: La fracción de eyección del ventrículo izquierdo puede ser determinada con una cámara CZT de alta sensibilidad, una reducción del 70% en actividades inyectadas y la calibración de cuentas adicional para realzar la concordancia con los valores de 2D-RNA. [Chinese] Chinese Abstract: 目的: 以平面放射性核素血管造影 (2D-RNA) 测定左心室射血分数 (EF) 作为参考标准,为确定利用高灵敏度 CZT SPECT 相机在减少 70% 的记录时间, 并结合计数校准防止高估情况下测量的 EF值, 是否与 2D-RNA 测得的 EF 值一致。 方法: 对心肌病 (n = 23) 或化疗监测 (n = 50) 的患者采用体内标记法注射 850 MBq {sup 99m}TcO{sub 4} 标记的红细胞进行 2D-RNA ,随后再采集 10 分钟 CZT-SPECT。 对 CZT-SPECT 100% 投影时间 (SPECT100) 或 30% 投影时间 (SPECT30) 获得的图像进行重建, 并进行计数校准 (对相应容积获得的 2D-RNA 计数通过 SPECT 校准)获得 EF 值, 与 2D-RNA 测定的 EF 的进行比较。 结果: 2D-RNA 测定的 EF 值与 SPECT100 校准后测定的 EF 值 (y = 0.89x + 6.62; R{sup 2} = 0.87) 及 SPECT30 (y = 0.87x + 8.40; R{sup 2} = 0.85) 校准后 EF 值具有高度相关性, 并且 SPECT100 (54 ± 15%) 和 SPECT30 (53 ± 16%) 测定的 EF 平均值与 2D-RNA 测定的 EF 平均值 (55 ± 15%) 非常接近。 但是, 在没有计数校准的情况下, SPECT100 (60 ± 18%) 和 SPECT30 (60 ± 18%) 测定的 EF 平均值会被高估。 结论: 高灵敏度 CZT 相机可在减少 70% 的注射剂量情况下测定左心室 EF 值, 结合计数校准可进一步提高与 2D-RNA测得的 EF 值的一致性。 关键词: 放射性核素血管造影; 血池 SPECT; CZT 相机; 左心室射血分数; 校准曲线。.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2000

Operational Implementation of a 2-Hour Prebreathe Protocol for International Space Station

Procedures, equipment, and analytical techniques were developed to implement the ground tested 2-hour protocol in-flight operations. The methods are: 1) The flight protocol incorporates additional safety margin over the ground tested protocol. This includes up to 20 min of additional time on enriched O2 during suit purge and pressure check, increased duration of extravehicular activity (EVA) preparation exercise during O2 prebreathing (up to 90 min vs; the tested 24 min), and reduced rates of depressurization. The ground test observations were combined with model projections of the conservative measures (using statistical models from Duke University and NASA JSQ to bound the risk of Type I and Type II decompression sickness (DCS). 2) An inflight exercise device using the in-flight ergometer and elastic tubes for upper body exercise was developed to replicate the dual cycle exercise in the ground trials. 3) A new in-flight breathing system was developed and man-tested. 4) A process to monitor inflight experience with the protocol, including the use of an in-suit Doppler bubble monitor when available, was developed. The results are: 1) The model projections of the conservative factors of the operational protocol were shown to reduce the risk of DCS to levels consistent with the observations of no DCS to date in the shuttle program. 2) Cross over trials of the dual cycle ergometer used in ground tests and the in-flight exercise system verified that02consumption and the % division of work between upper and lower body was not significantly different at the p= 0.05 level. 3) The in-flight breathing system was demonstrated to support work rates generating 75% O2(max) in 95 percentile subjects. 4) An in-flight monitoring plan with acceptance criteria was put in place for the 2-hour prebreathe protocol. And the conclusions are: The 2-hour protocol has been approved for flight, and all implementation efforts are in place to allow use of the protocol as early as flight ISS 7A, now scheduled in November of 2000.

Waligora, James M.↗
DOE OSTI2020

Systems and methods for monitoring a power-generation module assembly after a power-generation module shutdown event

Embodiments are directed to providing a user interface (UI) that streamlines and simplifies the process of monitoring critical power-generation module (PGM) parameters after a PGM assembly is shutdown. The UI displays, in real-time, indicators corresponding to one or more post-shutdown PGM parameters. The UI provides indications of whether the post-shutdown PGM parameters meet post-shutdown criteria of the PGM assembly. When a post-shutdown PGM parameter does not meet the post-shutdown criteria, a user alert is provided to the user. A protocol may additionally be provided to the user. In some embodiments, the protocol may enable the user to return the PGM assembly to a condition that satisfies the post-shutdown criteria. The protocol may be a safety protocol and/or an asset protection protocol.

Buenaventura, Don↗
DOE OSTI2022

Systems and methods for monitoring a power-generation module assembly after a power-generation module shutdown event

Embodiments are directed to providing a user interface (UI) that streamlines and simplifies the process of monitoring critical power-generation module (PGM) parameters after a PGM assembly is shutdown. The UI displays, in real-time, indicators corresponding to one or more post-shutdown PGM parameters. The UI provides indications of whether the post-shutdown PGM parameters meet post-shutdown criteria of the PGM assembly. When a post-shutdown PGM parameter does not meet the post-shutdown criteria, a user alert is provided to the user. A protocol may additionally be provided to the user. In some embodiments, the protocol may enable the user to return the PGM assembly to a condition that satisfies the post-shutdown criteria. The protocol may be a safety protocol and/or an asset protection protocol.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Adoption of a SAML-XACML profile for authorization interoperability across grid middleware in OSG and EGEE

The Authorization Interoperability activity was initiated in 2006 to foster interoperability between middleware and authorization infrastructures deployed in the Open Science Grid (OSG) and the Enabling Grids for E-sciencE (EGEE) projects. This activity delivered a common authorization protocol and a set of libraries that implement that protocol. In addition, a set of the most common Grid gateways, or Policy Enforcement Points (Globus Toolkit v4 Gatekeeper, GridFTP, dCache, etc.) and site authorization services, or Policy Decision Points (LCAS/LCMAPS, SCAS, GUMS, etc.) have been integrated with these libraries. At this time, various software providers, including the Globus Toolkit v5, BeStMan, and the Site AuthoriZation service (SAZ), are integrating the authorization interoperability protocol with their products. In addition, as more and more software supports the same protocol, the community is converging on LCMAPS as a common module for identity attribute parsing and authorization call-out. This paper presents this effort, discusses the status of adoption of the common protocol and projects the community work on authorization in the near future.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Relativistic quantum cryptography

A new protocol of quantum key distribution is proposed to transmit keys through free space. Along with quantum-mechanical restrictions on the discernibility of nonorthogonal quantum states, the protocol uses additional restrictions imposed by special relativity theory. Unlike all existing quantum key distribution protocols, this protocol ensures key secrecy for a not strictly one-photon source of quantum states and an arbitrary length of a quantum communication channel.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Secure multi-party communication with quantum key distribution managed by trusted authority

Techniques and tools for implementing protocols for secure multi-party communication after quantum key distribution ("QKD") are described herein. In example implementations, a trusted authority facilitates secure communication between multiple user devices. The trusted authority distributes different quantum keys by QKD under trust relationships with different users. The trusted authority determines combination keys using the quantum keys and makes the combination keys available for distribution (e.g., for non-secret distribution over a public channel). The combination keys facilitate secure communication between two user devices even in the absence of QKD between the two user devices. With the protocols, benefits of QKD are extended to multi-party communication scenarios. In addition, the protocols can retain benefit of QKD even when a trusted authority is offline or a large group seeks to establish secure communication within the group.

47 OTHER INSTRUMENTATION↗
DOE OSTI2015

Secure multi-party communication with quantum key distribution managed by trusted authority

Techniques and tools for implementing protocols for secure multi-party communication after quantum key distribution ("QKD") are described herein. In example implementations, a trusted authority facilitates secure communication between multiple user devices. The trusted authority distributes different quantum keys by QKD under trust relationships with different users. The trusted authority determines combination keys using the quantum keys and makes the combination keys available for distribution (e.g., for non-secret distribution over a public channel). The combination keys facilitate secure communication between two user devices even in the absence of QKD between the two user devices. With the protocols, benefits of QKD are extended to multi-party communication scenarios. In addition, the protocols can retain benefit of QKD even when a trusted authority is offline or a large group seeks to establish secure communication within the group.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Secure multi-party communication with quantum key distribution managed by trusted authority

Techniques and tools for implementing protocols for secure multi-party communication after quantum key distribution ("QKD") are described herein. In example implementations, a trusted authority facilitates secure communication between multiple user devices. The trusted authority distributes different quantum keys by QKD under trust relationships with different users. The trusted authority determines combination keys using the quantum keys and makes the combination keys available for distribution (e.g., for non-secret distribution over a public channel). The combination keys facilitate secure communication between two user devices even in the absence of QKD between the two user devices. With the protocols, benefits of QKD are extended to multi-party communication scenarios. In addition, the protocols can retain benefit of QKD even when a trusted authority is offline or a large group seeks to establish secure communication within the group.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

A practical method for efficient and optimal production of Seleno‐methionine‐labeled recombinant protein complexes in the insect cells

Abstract The use of Seleno‐methionine (SeMet) incorporated protein crystals for single or multi‐wavelength anomalous diffraction (SAD or MAD) to facilitate phasing has become almost synonymous with modern X‐ray crystallography. The anomalous signals from SeMets can be used for phasing as well as sequence markers for subsequent model building. The production of large quantities of SeMet incorporated recombinant proteins is relatively straightforward when expressed in Escherichia coli . In contrast, production of SeMet substituted recombinant proteins expressed in the insect cells is not as robust due to the toxicity of SeMet in eukaryotic systems. Previous protocols for SeMet‐incorporation in the insect cells are laborious, and more suited for secreted proteins. In addition, these protocols have generally not addressed the SeMet toxicity issue, and typically result in low recovery of the labeled proteins. Here we report that SeMet toxicity can be circumvented by fully infecting insect cells with baculovirus. Quantitatively controlling infection levels using our Titer Estimation of Quality Control (TEQC) method allow for the incorporation of substantial amounts of SeMet, resulting in an efficient and optimal production of labeled recombinant protein complexes. With the method described here, we were able to consistently reach incorporation levels of about 75% and protein yield of 60–90% compared with native protein expression.

Wenzel, Sabine↗
NASA NTRS2009

Survey of Software Problems with Impacts to 'Campout' Protocol Extravehicular Activity (EVA) Prebreathe

During International Space Station campout protocol ExtraVehicular Activity (EVA) preparations, the crew is isolated overnight in the small airlock volume in a reduced pressure, oxygen enriched atmosphere. As such, there are special considerations for the software in terms of air composition, pressure control and emergency responses. For one, the ISS software must monitor and manage two distinct atmospheres. Also, the small airlock volume is especially sensitive to small changes in the environment, and what would be a minor emergency in the larger vehicle volume can have catastrophic results in the isolated airlock. Finally, in cases of emergency, the crew needs to rapidly egress the airlock, which requires an aggressive automatic repressurization to equalize pressure on the hatch. This paper will describe the software which is modified for the airlock campout protocol. In addition, the paper will describe the software problems and hardware problems with software workarounds which have affected campout protocol.

Diderich, Greg↗
DOE OSTI2023

A Machine Learning Model for Predicting Composition of Catalytic Coprocessing Products from Molecular Beam Mass Spectra

Demand for the development of an automated and integrated refining process for biofuels has increased in recent years due to the lack of generalized process inspection tools. In bio-oil upgrading processes, all process variables are maintained based on the offline specification of intermediates and products. A lack of real-time product specifications in batch-wise monitoring can cause process failure and wasted resources. Therefore, there is a need for a fast and accurate intermediates/product specification tool that can be used for real-time specification to reduce waste and mitigate the risk of process failure. Here, to address this gap, we developed a machine learning (ML) model for predicting speciated bio-oil composition, including paraffin, iso-paraffins, olefins, naphthene, and aromatics. The model is trained using the mass spectra from upgraded products collected in the vapor phase before condensation and predicts the composition of the condensed product. Training ML models using raw mass spectra is challenging due to numerous overlapped peaks originating from different parent compounds. With this in mind, we propose a protocol that (i) transforms raw mass spectra to chemistry-inspired predefined features and (ii) trains decision tree-based models using these features. Our results show that the random forest model was robust against overfitting and had the highest accuracy compared to other models. Moreover, a stochastic ablation method determined the eight most significant features while maximizing the accuracy. Our protocol facilitates real-time compositional analysis of upgraded bio-oils and thus real-time process monitoring. Additionally, this protocol enables the rational design of efficient catalysts and the determination of optimal process conditions.

09 BIOMASS FUELS↗
DOE OSTI2022

Protocol for single-cell isolation and genome amplification of environmental microbial eukaryotes for genomic analysis

We describe environmental microbial eukaryotes (EMEs) sample collection, single-cell isolation, lysis, and genome amplification, followed by the rDNA amplification and OTU screening for recovery of high-quality species-specific genomes for de novo assembly. These protocols are part of our pipeline that also includes bioinformatic methods. The pipeline and its application on a wide range of phyla of different sample complexity are described in our complementary paper. In addition, this protocol describes optimized lysis, genome amplification, and OTU screening steps of the pipeline. For complete details on the use and execution of this protocol, please refer to Ciobanu et al. (2021).

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Effective methylation of phosphonic acids related to chemical warfare agents mediated by trimethyloxonium tetrafluoroborate for their qualitative detection and identification by gas chromatography-mass spectrometry

The effective methylation of phosphonic acids related to chemical warfare agents (CWAs) employing trimethyloxonium tetrafluoroborate (TMO·BF 4 ) for their qualitative detection and identification by gas chromatography-mass spectrometry (GC-MS) is presented. The methylation occurs in rapid fashion (1 h) and can be conveniently carried out at ambient temperature, thus providing a safer alternative to the universally employed diazomethane-based methylation protocols. Optimization of the methylation parameters led us to conclude that methylene chloride was the ideal solvent to carry out the derivatization, and that even though methylated products can be observed surfacing after only 1 h, additional time was not found to be detrimental but beneficial to the process particularly when dealing with analytes at low concentrations (~10 μg mL -1 ). Due to its insolubility in methylene chloride, TMO·BF 4 conveniently settles to the bottom during the reaction and does not produce additional interfering by-products that may further complicate the GC-MS analysis. We demonstrated the method to successfully methylate a variety of Schedule 2 phosphonic acids, including their half esters, resulting in derivatives that were readily detected and identified using the instrument's spectral library. Most importantly, the method was shown to simultaneously methylate a mixture of the organophosphorus-based nerve agent hydrolysis products: pinacolyl methylphosphonate (PMPA), cyclohexyl methylphosphonate (CyMPA) and ethyl methylphosphonate (EMPA) (at a 10 μg mL - 1 concentration each) in a fatty acid ester-rich organic matrix (OPCW-PT-O 3 ) featured in the 38th Organisation for the Prohibition of Chemical Weapons (OPCW) Proficiency Test. Additionally, the protocol was found to effectively methylate N,N-diethylamino ethanesulfonic acid and N,N-diisopropylamino ethanesulfonic acid that are products arising from the oxidative degradation of the V-series agents VR and VX respectively. This work described herein represents the first report on the use of TMO·BF 4 as a viable, stable and safe agent for the methylation of phosphonic acids and their half esters and within the context of an OPCW Proficiency Test sample analysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

An efficient protocol for radiochromic film dosimetry combining calibration and measurement in a single scan

Purpose: Radiochromic film provides dose measurement at high spatial resolution, but often is not preferred for routine evaluation of patient-specific intensity modulated radiation therapy (IMRT) plans owing to ease-of-use factors. The authors have established an efficient protocol that combines calibration and measurement in a single scan and enables measurement results to be obtained in less than 30 min. This avoids complications due to postexposure changes in radiochromic film that delay the completion of a measurement, often for up to 24 h, in commonly used methods. In addition, the protocol addresses the accuracy and integrity of the measurement by eliminating environmental and interscan variability issues. Methods: The authors collected dose-response data from six production lots of Gafchromic EBT3 film and three production lots of EBT2 film at doses up to 480 cGy. In this work, the authors used seven different scanners of two different models-Epson 10000XL and V700; postexposure times before scanning from 30 min to 9 days; ambient temperatures for scanning spanning 11 Degree-Sign C; and two film orientations. Scanning was in 48-bit RGB format at 72 dpi resolution. Dose evaluation was conducted using a triple-channel dosimetry method. To evaluate the measurement protocol, patient specific IMRT and volumetric modulated arc therapy (VMAT) plans were exposed onto EBT3 films on a Varian Trilogy Linac. Film scanning was done following the protocol under a number of different conditions and the dose maps were analyzed to demonstrate the equivalence of results. Results: The results indicated that the dose-response data could be fit by a set of related rational functions leading to the description of a generic calibration curve. A simplified dosimetry protocol was established where dose-response data for a specific film lot, scanner, and scanning conditions could be derived from two films exposed to known doses. In most cases only one calibrated exposure was required since the dose for one of the films could be zero. Using the Gamma test criterion of 2%/2 mm to evaluate the measurements, similar passing rates ranging between about 95% and 99% for the fields studied were obtained from application films digitized under a variety of conditions all of them different than the conditions under which the calibration films were scanned. Conclusions: The authors have developed a simplified and efficient protocol to measure doses delivered by an IMRT or VMAT plan using only the patient film, one calibration film, one unexposed film, and applying a single scan to acquire a digital image for calculation and analysis. The simplification and timesaving offer a potential practical solution for using radiochromic film for routine treatment plan quality assurance without sacrificing spatial resolution for convenience.

07 ISOTOPE AND RADIATION SOURCES↗