Engineering upgrades to the Radionuclide Aerosol Sampler/Analyzer for the CTBT International Monitoring System

The Radionuclide Aerosol Sampler/Analyzer (RASA) is an automated collection and analysis system designed for aerosol radionuclide monitoring for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The advantages of an automated system include minimal need for human intervention and consistent analytical data. However, maintainability and down time issues threaten this utility, even for systems with over 90 % data availability. Engineering upgrades to the RASA are currently being pursued to address these issues, as well as measures relevant to technical lessons learned from the Fukushima nuclear power plant event. Current work includes a new automation control unit and other potential improvements such as alternative detector cooling and sampling options. This paper presents the current state of upgrades and improvements under investigation.     

Automated separation and measurement of radioxenon for the Comprehensive Test Ban Treaty

A fully automatic radioxenon sampler/analyzer (ARSA) has been developed and demonstrated for the collection and quantitative measurement of the four xenon radionuclides,^131mXe(11.9 d),^133mXe(2.2 d),¹³³Xe(5.2 d), and¹³⁵Xe(9.1 hr), in the atmosphere. These radionuclides are important signatures in monitoring for compliance to a Comprehensive Test Ban Treaty (CTBT). Activity ratios of these radionuclides permit source attribution. Xenon, continuously and automatically separated from the atmosphere, is automatically analyzed by electron-photon coincidence spectrometry providing a lower limit of detection of about 100 μBq/m³. The demonstrated detection limit is about 100 times better than achievable with reported laboratory-based procedures for the short-time collection intervals of interest.     

Field testing of collection and measurement of radioxenon for the Comprehensive Test Ban Treaty

Pacific Northwest National Laboratory, with guidance and support from the U.S. Department of Energy's NN-20 Comprehensive Test Ban Treaty (CTBT) Research and Development program, has developed and demonstrated a fully automatic sampler-analyzer (ARSA) for the collection and quantitative measurement of the four xenon radionuclides,^131mXe (11.9 d),^133mXe (2.19 d),¹³³Xe (5.24 d), and¹³⁵Xe (9.10 h), in the atmosphere. These radionuclides are important signatures in monitoring for compliance to a CTBT, and may have applications in stack monitoring and other areas where xenon radionuclides are present. The activity ratios between certain of these radionuclides permit discrimination between radioxenon originating from nuclear detonations and that from nuclear reactor operations, nuclear fuel reprocessing, or from medical isotope production and usage. With the ARSA system, xenon is continuously and automatically separated from the atmosphere at flow rates of about 100 lpm by sorption-bed techniques. Samples collected in 8 hours are automatically analyzed by electron-photon coincidence spectrometry to provide detection sensitivities as low as 100 μBq/m³ of air. This sensitivity is about 10-fold better than achieved with reported laboratory-based procedures¹ for the short time collection intervals of interest. Gamma-ray energy spectra and gas analysis data are automatically collected.     

Application of the nuclide identification system SHAMAN in monitoring the Comprehensive Test Ban Treaty

SHAMAN is an expert system for qualitative and quantitative radionuclide identification in gamma spectrometry. SHAMAN requires as input the calibrations, peak search, and fitting results from reliable spectral analysis software, such as SAMPO. SHAMAN uses a comprehensive reference library with 2600 radionuclides and 80 000 gamma-lines, as well as a rule base consisting of sixty inference rules. Identification results are presented both via an interactive graphical interface and in the form of configurable text reports. An organization has been established for monitoring the recent Comprehensive Test Ban Treaty. For radionuclide monitoring, 80 stations will be set up around the world. Air-filter gammaspectra will be collected from these stations on a daily basis and they will need to be reliably analyzed with minimum turnaround time. SHAMAN is currently being evaluated within the prototype monitoring system as an automated radionuclide identifier, in parallel with existing radionuclide identification software. In air-filter monitoring, very low concentrations of radionuclides are measured from bulky sources in close geometry and with long counting time. In this case true coincidence summing and self-absorption become important factors. SHAMAN is able to take into account these complicated phenomena, and the results it produces have been found to be very reliable and accurate.     

测量复方药物溶出度的全自动药物溶出度测定仪

自行设计组装了一套可以同时测定复方药剂的全自动药物溶出度测定仪。该仪器由光学检测系统（由光源、流动型吸收池，小型光谱仪组成）、自动进样系统、控制与数据处理系统和机械搅拌系统4部分组成。光学系统的检测器是线阵电荷耦合器件（CCD），故可进行同时全光谱采集。数据处理部分采用了自行设计的基于径向基函数的人工神经网络进行浓度预测。用本装置对市售复方药剂鲁南贝特进行的溶出度测量表明，测量的精密度高，准确度较高，分析速度快，样品无需前处理。     

测量复方药物溶出度的全自动药物溶出度测定仪

自行设计组装了一套可以同时测定复方药剂的全自动药物溶出度测定仪.该仪器由光学检测系统(由光源、流动型吸收池,小型光谱仪组成)、自动进样系统、控制与数据处理系统和机械搅拌系统4部分组成.光学系统的检测器是线阵电荷耦合器件(CCD),故可进行同时全光谱采集.数据处理部分采用了自行设计的基于径向基函数的人工神经网络进行浓度预测.用本装置对市售复方药剂鲁南贝特进行的溶出度测量表明,测量的精密度高,准确度较高,分析速度快,样品无需前处理.     

Implementation of radionuclide measurements for the Comprehensive Nuclear-Test-Ban Treaty and associated on-site inspections

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) plans the installation of an International Monitoring System (IMS) based upon four global networks. Seismic, hydroacoustic and infrasound waves will help detect underground, underwater and atmospheric nuclear tests and will permit their discrimination from natural events. 80 particulate stations will detect radioactive aerosols, this network being completed with a sub-set of 40 stations which will measure rare gases, typically xenon isotopes. 16 IMS laboratories will perform additional analysis mainly by gamma-spectrometry, using the most sensitive methods such as particulate analysis. In order to have the most effective network, modeling was performed by using an inverse method in which the radioactive tracer is transported back from detectors. Examples will be given, regarding the maps of detection probability, background effects of existing xenon or radon, or the decoupling effects. All these tools and means are anticipated to have a complete process of certification, authentication of the data and discrimination capabilities between nuclear test and releases from civilian nuclear industry (reactors, reprocessing plants,). If a State Party identifies events that it feels could be a nuclear explosion, it can ask for clarification and finally it may send a request for an On-Site Inspection. The rights of the State Party and the constraints for the Inspection Team are defined in the Treaty. That leads to limited time, to limited number of inspectors on the site and to precise methods to be authorized. The means and resulting data have to be blinded in order to make sure the confidentiality is observed. Examples of restricting measurements will be given regarding airborne or vehicle mounted spectrometry as well as laboratory analysis. Cooperation with international organizations (WMO, WHO) will be discussed, depending on confidentiality issues.     

Experience of the Finnish National Data Centre in radionuclide analysis for the Comprehensive Nuclear-Test-Ban Treaty

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is setting very specific requirements to processing of gamma-ray spectra. All the data collected in 80 radionuclide particulate stations are transmitted to the International Data Centre (IDC), where they are analyzed. National Data Centres (NDC) are the users of IDC services. The NDC's are responsible of giving technical information to National Authorities, who have thepolitical responsibility of the compliance to the treaty. The IDC analysis is not directly informing if a nuclear test has been conducted; it is just categorizing the spectra to help the NDC's to make their decision. An NDC must have a high confidence on the correctness of the radionuclide analyses the IDC, and the NDC itself, are performing. Special attention must be paid to Event Screening, where the NDC, among other things, needs a historical record of the measured data to be able to ignore the occasionally occurring fission products, for example. The amount of data produced is too large for an NDC to process interactively. Therefore, batch-processing capabilities are required from the NDC. The Finnish NDC is involved in evaluating of the IDC processing and software and it is also proposing a radionuclide processing solution for other NDC's, as well.     

碳酸盐含量自动分析仪的性能测试

作者采用库仑滴定原理，利用光电转换、微机控制电解终点，研制了一台碳酸盐含量自动分析仪。本文介绍了有关仪器性能测试方面的工作，包括对碳酸盐标样（９９．９９％的优级纯ＣａＣＯ３）的测试，准确度达０．０８％，精密度为０．８７％；并与定容测压方法进行了比较，本仪器对油田、沉积物样品进行的测试表明具有分析准确度高、分析速度快、用样量少、自动化程度高等优点。适合在石油、沉积、矿床及第四纪等领域应用。     

易挥发液体样品采样器(Ⅱ型)的研制及性能

研究了一种易挥发液体样品采样器（Ⅱ型），它具有采样准确、使用方便、容易清洗和携带等优点，配合气相色谱仪，可满足轻质油品等易挥发液体样品的采样分析要求。     

AOT/异辛烷/水微乳液中结晶紫与AOT相互作用的热力学研究

用紫外-可见分光光度法在不同温度下测定了结晶紫(CV)在双-2-乙基己基硫代琥珀酸钠(气溶胶OT或AOT)为表面活性剂的W/O微乳液中的吸光度. 根据结晶紫和AOT在微乳液水滴界面缔合的模型对实验数据进行处理, 结果表明, 随着微乳液中水与AOT的摩尔比w的减小和温度的升高, 结晶紫缔合度增大, 根据不同温度下的缔合平衡常数计算了反应的热力学函数, Δ_rG_m, Δ_rH_m和Δ_rS_m     

A Gaseous Nitric Acid Analyzer for the Remote Atmosphere Based on the Scrubber Difference/NO-Ozone Chemiluminescence Method

An in situ nitric acid analyzer has been designed for sensing in the remote atmosphere. Its operation is based on measuring the concentration difference between the total odd nitrogen species (NO(y)) and HNO(3)-scrubbed NO(y). NO(y) was measured by an NO-ozone chemiluminescent detector equipped with a molybdenum converter. A temperature-controlled annular denuder coated with NaCl was used as a scrubber of gaseous HNO(3). The current detection limit of the HNO(3) analyzer was estimated to be 158 and 71 pptv (parts per trillion by volume) with an integration time of 2 and 10 min (2sigma), respectively. The analyzer was calibrated using standard gaseous HNO(3) to verify its performance. The HNO(3) concentrations measured by the scrubber difference and the NO-ozone chemiluminescence methods (SDCL method) were in agreement with those obtained by the denuder method within the experimental uncertainties (more than +/-4%). We conducted limited field observations of NO(y) and HNO(3) in the remote atmosphere using the newly designed SDCL method at Cape Hedo, Okinawa, Japan.     

Comprehensive description of the photodegradation of bromophenols using chromatographic monitoring and chemometric tools

A general procedure for the study of complex photodegradation processes of environmental pollutants based on chromatographic monitoring and chemometric method is proposed. The procedure consists of multiset data analysis of aliquots collected at different reaction times and injected in High-Performance Liquid Chromatography coupled to diode array detection and mass spectrometry (HPLC-DAD-MS). In this study, photodegradation of six bromophenols with different degrees of bromination has been investigated in order to find out their photodegradation pathways and kinetics and to show the potential of the procedure proposed. Multivariate curve resolution-alternating least squares (MCR-ALS) has been used to resolve chromatographic elution profiles and pure spectra of species involved in the photodegradation process and, hence, to elucidate the photodegradation mechanism and to propose the chemical structure of the main photoproducts. This study shows that chromatographic monitoring is the preferred option when photochemical systems with large number of components with similar spectra and kinetic evolution are analyzed. This work reveals the advantages of the double DAD and MS detection to provide mechanistic and structural information about these complex photodegradation processes.     

高频红外碳硫仪在成分分析中的应用

本文使用HF86 8型高频感应燃烧炉及HCS878A型红外碳硫仪对普碳钢、高低合金钢、铸生铁、铁合金 (锰铁、硅铁、钼铁、铬铁、磷铁 )、焦炭、煤、铁矿石等分析 ,结果准确、精密度高 ,分析速度快。1　试验部分1.1　主要仪器HCS878A型红外碳硫仪、HF86 8型高频感应燃烧炉 (四川省德阳市科学仪器厂 )。1.2　试验条件铁样、钢样、硅铁、锰铁、磷铁、钛铁、铁矿石、硅钙合金、钼铁等样品称样量为 0 .10 .5 g ,煤、焦碳样品称样量为 5 0mg。分析钢、铁、磷铁、钛铁、钼铁加4 0目的钨粒作助熔剂 ;分析铁矿石加钨粒、三氧化钼、纯铁作助熔剂 ;硅铁…     

A viscoelastic description of the glass transition-conversion relationship for reactive polymers

The glass transition temperature,T _g is a sensitive and practical parameter for following cure of reactive thermosetting systems. A new equation was developed for predicting theT _g -conversion relationship based on the Dillman-Seferis viscoelastic compliance model. It assumes that the changes inT _g are primarily due to changes in relaxation time as chain extension and crosslinking reduce the mobility of a polymer network. Such information is essential in combining kinetic and viscoelastic measurements, which monitor transformations of thermosets during cure. The equation derived from the viscoelastic model was shown to be applicable for a variety of experimental data. The success of the methodology was further demonstrated by comparing well-established relations, such as the Fox equation and the Di-Benedetto equation, to predictions made possible by adjusting two viscoelastic model parameters. Finally, the fitting power of the proposed equation was shown by fitting published epoxy data from the literature as well as experimental data on a relatively new resin system such as dicyanates used as a model in this study.Der GlasumwandlungspunktT _g ist eine empfindliche und praktische Grö\e zum Verfolgen der AushÄrtung reaktiver Duroplaste. Basierend auf dem viskoelastischen Steifigkeitsmodell von Dillman-Seferis wurde eine neue Gleichung zur Vorhersage der Beziehung zwischenT _g und Konversion entwickelt. Dabei wird angenommen, da\ die Änderung vonT _g in erster Linie durch eine Änderung der Relaxationszeit bedingt ist, da KettenverlÄngerung und Vernetzung die Beweglichkeit des Polymergefüges herabsetzen. Bei einer Kombination von kinetischen und viskoelastischen Messungen, mit denen die Umwandlungen wÄhrend des AushÄrtens von Duroplasten verfolgt werden können, ist diese Erkenntnis von gro\er Bedeutung. Die auf der Basis des viskoelastischen Modelles erhaltene Gleichung ist für eine gro\e Breite von experimentellen Daten anwendbar. Den Erfolg dieser Methodik zeigt weiterhin ein Vergleich bewÄhrter Beziehungen, wie z.B. der Foxschen Gleichung und der Gleichung von DiBenedetto, mit Aussagen, die durch Anpassung zweier viskoelastischer Parameter ermöglicht wurden. Die StÄrke der vorgeschlagenen Gleichung wird letztlich durch Anpassen von Epoxy-Daten aus der Literatur sowie von experimentellen Daten eines relativ neuen und in dieser Untersuchung als Modell benutzten Harzsystemes gezeigt.     

A molecular description of the evolution of resistance

BACKGROUND: In vitro evolution has been used to obtain nucleic acid molecules with interesting functional properties. The evolution process usually is carried out in a stepwise manner, involving successive rounds of selection, amplification and mutation. Recently, a continuous in vitro evolution system was devised for RNAs that catalyze the ligation of oligonucleotide substrates, allowing the evolution of catalytic function to be studied in real time. RESULTS: Continuous in vitro evolution of an RNA ligase ribozyme was carried out in the presence of a DNA enzyme that was capable of cleaving, and thereby inactivating, the ribozyme. The DNA concentration was increased steadily over 33.5 hours of evolution, reaching a final concentration that would have been sufficient to inactivate the starting population in one second. The evolved population of ribozymes developed resistance to the DNA enzyme, reducing their vulnerability to cleavage by 2000-fold but retaining their own catalytic function. Based on sequencing and kinetic analysis of the ribozymes, two mechanisms are proposed for this resistance. One involves three nucleotide substitutions, together with two compensatory mutations, that alter the site at which the DNA enzyme binds the ribozyme. The other involves enhancement of the ribozyme's ability to bind its own substrate in a way that protects it from cleavage by the DNA enzyme. CONCLUSIONS: The ability to direct the evolution of an enzyme's biochemical properties in response to the behavior of another macromolecule provides insight into the evolution of resistance and may be useful in developing enzymes with novel or enhanced function.     

A method for determining a basis set suitable for the description of radiationless decay

Quantitative conditions are derived which a basis set must satisfy if it is to be used for describing radiationless decay. The derivation is valid for both internal conversion and intersystem crossing.