Characterisation of the steady state tube furnace (ISO TS 19700) for fire toxicity assessment

The steady state tube furnace (Purser furnace, ISO TS 19700) has been developed specifically to replicate the generation of toxic products from real fires under different fire conditions on a bench-scale. Steady state burning is achieved by driving the sample into a furnace of increasing heat flux at a fixed rate and recording the product yields over a steady state period in the middle of the run. The furnace, sample, and effluent dilution chamber temperature profiles are presented to characterise the conditions in the apparatus. The distribution of smoke in the mixing chamber has been investigated to demonstrate the efficiency of mixing in the effluent dilution chamber. The heat flux applied to the sample at various points through the furnace has been measured, showing that conditions vary from those typical of pre-flaming to fully developed fires. An initial investigation of the repeatability and interlaboratory reproducibility has been undertaken, showing acceptable low levels of uncertainty in the toxic product yields.     

An automated evolved gas detection apparatus

An automated evolved gas detection apparatus is described consisting of a furnace, furnace temperature programmer, automatic sample changer, thermistor thermal conductivity detector, and a two channel recorder. The samples are automatically introduced into the furnace chamber, pyrolyzed to a preselected temperature limit, and then removed. After the system has cooled to a preselected lower temperature limit, the cycle is repeated. Eight samples can be studied in a sequential manner.     

Proben-Abhängigkeit (PA) curves and simple anhydrous carbonate minerals

Marked modifications to carbonate DTA curves are caused by variations in the partial pressure of CO₂ gas in the furnace atmosphere. Calcite is used to illustrate the curve configurational changes which may occur. Attention is drawn to the effects of variations in: thermal conductivity of the gases used as furnace atmospheres, the furnace access to the ambient atmosphere, the volume of the furnace “tube“ and the size of the sample (and therefore the amount of self generated CO₂). These effects emphasise the care with which the constancy of DTA determination conditions must be maintained for content evaluation methods such as “Proben-Abhängigkeit“ curves.     

Novel instrument for high temperature thermogravimetric measurements in high water vapour contents

Summary A novel instrument for high temperature thermogravimetric measurements in atmospheres containing high water vapour contents was developed in a collaboration between Netzsch and Risø National Laboratory. The development of the instrument was initiated to facilitate the investigation of high temperature corrosion of steels in humidified atmospheres. The instrument consists of a standard thermal analyser unit, including a new water vapour furnace, balance and sample carrier. The design of the instrument is discussed and thermogravimetric measurements on a Fe₇₈Cr₂₂ steel are presented.     

Stabilization of moisture-reactive raw materials for improved synthesis of Ca-α-SiAlON:Eu2+ phosphor

The raw materials needed to make the Ca-α-SiAlON:Eu²⁺ phosphor contain highly moisture-reactive Ca₃N₂. Exposing them to a preheating process prior to high-temperature synthesis stabilized the raw materials against oxidation. Preheating above 1200 °C in a tube furnace directly connected to a glove box, resulted in the formation of intermediate phases such as CaAlSiN₃, which provided higher moisture resistance to the raw materials. We found that even after exposure to a humid environment, the preheated samples maintained PL characteristics similar to the conventional unexposed samples, while the PL intensity and particle homogeneity of the un-preheated samples were severely deteriorated.     

DNA微阵列原位合成中的氧化剂体系改进

DNA芯片的制备方法主要有离片合成法和在片合成法．离片合成是用点样法将DNA探针固定在基片上;在片合成是在基片表面直接原位合成寡核苷酸探针阵列．目前国外已有多种DNA芯片原位合成方法的报道,但其中仅Fordor等提出的光脱保护DNA固相原位合成技术已商品化,该方法制备成本高,     

Spark-Source Mass Spectrometric Techniques for the Analysis of Lanthanide and Actinide Elements in Microgram and Sub-Microgram Transuranium Samples

Abstract

Lanthanide and actinide impurities in a total sample of 1 to 10 μg of transuranic matrix can be determined by employing the spark-source mass spectrograph and solution technique. A special source glove box permits safe manipulation of transuranium elements with α-emitting radioactivity up to 10¹² dpm. The minimum detection limit is about 10¹² atoms per electrode system and an exposure of 10^?8 coulomb. Relative sensitivity values for the lanthanides and actinides were established with respect to erbium, the internal standard.     

Initial study of a combustion-mass spectrometric system for organic microanalysis

A combustion-mass spectrometric system has been designed and studied for simultaneous determining C, N and S compositions of organic compounds. The system is constructed by linking a high-temperature combustion furnace with a quadrupole mass selected detector. A solid or liquid organic sample is directly dropped into the quartz reactor within the furnace where it is combusted and converted into gaseous CO₂, N₂, and SO₂. The resulting gases are mixed thoroughly in a chamber prior to being introduced, through a high-precision metering valve, into the ion source of the mass spectrometer. After performing a series of optimization studies, we examined the analytical performance of the system by testing the precision and linearity of calibration. The initial study indicates that good analytical sensitivity and precision can be obtained for C, N, and S even with 0.2 mg of sample, approximately 1/10 of what is required using traditional combustion-thermal conductive detector (TCD) method. The use of 0.1% argon in the helium working gas as an internal standard further improves the analytical precision. The typical R.S.D. obtained is in the range of 0.43-1.10% depending on the analyte. Another feature of this system is that it not only yields quantitative data, but also helps monitoring the combustion efficiency for analytes eluting through the combustion furnace. This feature can perhaps be utilized to establish suitable experimental conditions and monitor combustion process, especially of large and refractory compounds, thus ensuring the accuracy of the microanalysis.     

Quasi in situ XPS investigations on intercalation mechanisms in Li-ion battery materials

New concepts for Li-ion batteries are of growing interest for high-performance applications. One aim is the search for new electrode materials with superior properties and their detailed characterization. We demonstrate the application of X-ray photoelectron spectroscopy (XPS) to investigate electrode materials (LiCoO₂, LiCrMnO₄) during electrochemical cycling. The optimization of a “quasi in situ” analysis, by transferring the samples with a transport chamber from the glove box to the XPS chamber, and the reliability of the experiments performed are shown. The behavior of characteristic chemical species at the electrodes and the changes in oxidation states of LiCrMnO₄ during cycling is discussed. The formation of Cr⁶⁺ is suspected as a possible reason for irreversible capacity loss during charging up to complete Li deintercalation (approximately 5.2 V). Figure Scheme of a quasi in situ XPS experiment on Li-ion battery electrode material     

Automated gravimetric sample pretreatment using an industrial robot for the high-precision determination of plutonium by isotope dilution mass spectrometry.

A robotized sample-preparation method for the determination of Pu, which is recovered by extraction reprocessing of spent nuclear fuel, by isotope dilution mass spectrometry (IDMS) is described. The automated system uses a six-axis industrial robot, whose motility is very fast, accurate, and flexible, installed in a glove box. The automation of the weighing and dilution steps enables operator-unattended sample pretreatment for the high-precision analysis of Pu in aqueous solutions. Using the developed system, the Pu concentration in a HNO(3) medium was successfully determined using a set of subsequent mass spectrometric measurements. The relative uncertainty in determining the Pu concentration by IDMS using this system was estimated to be less than 0.1% (k = 2), which is equal to that expected of a talented analyst. The operation time required was the same as that for a skilled operator.     

Industrial production and purification of <Superscript>32</Superscript>P by sulfur irradiation with partially moderated neutron fluxes and target melting

Target purification of S_α is carried out by distillation at 444±2 °C under N atmosphere and diluting the vapors in CS₂. The solution is filtered through fiberglass, Teflon and cellulose to obtain S_α by CS₂ evaporation. Once 30 g of this target are irradiated with fast neutron fluxes from 4.5 to 7.4·10¹² n·cm⁻²s⁻¹ from 6 to 12 hours, the nuclear reaction ³²S(n,p)³²P takes place. So, the irradiated S_α sample is placed in a Pyrex container situated inside a furnace as the most important piece of equipment in one aluminum and Lucite glove box. The distillation of irradiated sulfur takes place at 444±2 °C under N atmosphere during 1–2 hours. The vapors are connected to a sulfur diluter containing 20% CS₂ aqueous solution, followed by an activated carbon filter and the two similar additional sulfur diluters. Once cooled, the distillation chamber keeps the radioactive, carrier-free ³²P stuck to the wall. Then 25–50 ml of 0.1N HCl acid was injected by suction and heated again at 110±2 °C during 1 hour. The corresponding chemical reaction takes place and the labeled H₃ ³²PO₄ solution is produced. In such a way, industrial production of ³²P labeled molecules has started in Mexico, with an initial production of 3700–5550 MBq per week.     

Analysis of long-lived radionuclides by ICP-MS

Inductively Coupled Plasma Mass Spectrometry ICP-MS has been applied to the characterisation of various nuclear waste forms. Long-lived radionuclides can be determined with similar sensitivities. The installation of an ICP-MS in a glove box and applications and limitations of the methods to nuclear materials, with especial emphasis on isobaric interferences are described.     

Role of the reactive atmosphere during the sol–gel synthesis on the enhancing of the emission quantum yield of urea cross-linked tripodal siloxane-based hybrids

Transparent monoliths and films of urea cross-linked tripodal siloxane-based hybrids (named tri-ureasils) were prepared by the sol–gel process, under controlled atmosphere (inside a glove box) and ambient conditions and their structure and optical features were compared. X-ray diffraction data point out that all the materials are essentially amorphous and ²⁹Si NMR reveal an increase in the condensation degree (0.97) for the hybrids prepared under controlled atmosphere relatively to that found for those prepared under ambient conditions (0.84–0.91). The tri-ureasils are white light emitters under UV/Visible excitation (from 250 to 453 nm) being observed for the composites prepared inside the glove box a significant enhancement (60–80 %) of the absorption coefficient and higher emission quantum yield values (~0.27 and ~0.20 for monoliths and films, respectively) relatively to those synthesized under ambient condition.     

Electrolytical enrichment for liquid scintillation determinations of low tritium samples: A revised methodology

The determination of carbon, hydrogen, nitrogen, fluorine, chlorine and sulphur contents for characterization of plutonium complexes with organic ligands have been standardized and glove box adopted. Various plutonium(IV) mono- and di-carboxylates, plutonium(IV) chelates with pyrazolones, UO ₂ ⁺⁺ and PuO ₂ ⁺⁺ complexes having pyrazolones as chelating agent and sulfoxides, amides and phosphine oxide ligands as oxodonors; uranium carbides and uranium nitrides and several potential organic extractants for actinides were analyzed satisfactorily. All these methods set up in double module glove box train are extremely useful for a low budget radioactive laboratory engaged in research in solid actinide complexes.     

The thermal decomposition reactions of [Co(en)n(phen)m]Cl3 complexes

The thermal behaviour of [Co(en)_n(phen)_m]Cl₃ complexes has been studied using thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) in air, nitrogen and oxygen atmospheres. The effect of the stoichiometry of the complexes and that of the gas atmosphere in the furnace chamber on the thermal decomposition reaction is evidenced and discussed. The following thermal stability order has been found [Co(en)₃]Cl₃ [Co(en)₂(phen)]Cl₃ > [Co(en)(phen)₂]Cl₃ [Co(phen)₃]Cl₃     

TAG高温氧化腐蚀分析仪原理及应用

介绍了TAG高温氧化腐蚀分析仪的结构特点、工作原理及具体应用. TAG高温氧化腐蚀分析仪能够在可控气氛(干燥、潮湿和腐蚀)和可控温度的条件下实现原位测试. 双炉体设计最大程度上减小了浮力效应的干扰,并且悬挂样品设计全面积接触气氛,精确测量质量微弱变化. TAG高温氧化腐蚀分析仪可用于研究无机和有机材料等的高温分解问题,也可用于研究金属和陶瓷等材料在单一或多种气氛下的氧化腐蚀机理.     

Measurement of evolved gas resulting from closed-system pyrolysis of foundry core binders

The quantity of gas generated by pyrolysis of a foundry core binder during casting operations is of practical importance to the foundry industry. A method for measuring the gas volume was developed using a DuPont 951 TGA furnace system; this method eliminates many of the errors inherent in some of the traditional methods. The incorporation of an extrapolation technique eliminates the dependence of the final result on sample size. This method was found to be rapid, highly reproducible, and insensitive to the nature of the atmosphere in the pyrolysis chamber.     

Use of DSC and DMA to study crystallization as a possible cause for a glove tear

The Advanced Crew Escape Suit (ACES) is a pressurized suit worn by astronauts during launch and landing phases of Space Shuttle operations. In 2008, a large tear (12.7–25.4 mm long, between the pinky and ring finger) in the ACES left-hand glove made of neoprene latex rubber was found during training for Shuttle flight STS-124. An investigation to help determine the cause(s) of the glove tear was headed by the NASA Johnson Space Center (JSC) in Houston, Texas. Efforts at JSC to reproduce the actual glove tear pattern by cutting/tearing or rupturing were unsuccessful. Chemical and material property data from JSC such as GC-MS, FTIR, DSC, and TGA mostly showed little differences between samples from the torn and control gloves. One possible cause for the glove tear could be a wedding ring/band worn by an astronaut. Even with a smooth edge, such a ring could scratch the material and initiate the tear observed in the left-hand glove. A decision was later made by JSC to not allow the wearing of such a ring during training or actual flight. Another possible cause for the ACES glove tear is crystallinity induced by strain in the neoprene rubber over a long period of time and use. Neoprene is one among several elastomers known to be susceptible to crystallization, and such a process is accelerated with exposure of the material to cold temperatures plus strain. When the temperature is lowered below room temperature, researchers have shown that neoprene crystallization may be maintained at temperatures as high as 7.2–10 °C, with a maximum crystallization rate near −6.7 to −3.9 °C (Kell et al. J Appl Polym Sci 2(4):8–13, 1959 [1]). A convenient conditioning temperature for inducing neoprene crystallization is a typical freezer that is held near −17.8 °C. For work at the NASA Marshall Space Flight Center (MSFC), samples were cut from several areas/locations (pinky/ring finger crotch, index finger and palm) on each of two pairs of unstrained ACES gloves for DSC and DMA thermal analysis testing. The samples were conditioned in a freezer for various times up to about 14 days. Some rectangular conditioned samples were unstrained, while most were subjected to strains up to 250% with the aid of two slotted aluminum blocks and two aluminum clamps per sample. Trends were observed to correlate DSC data (heat of fusion) and DMA data (linear CTE and stress for iso-strain testing) with (a) sample location on each glove; and (b) percent strain during conditioning. Control samples cut “as is” from each glove location were also tested by DSC and DMA.     

Investigation of graphite-probe atomisation for carbon-furnace atomic emission spectrometry

A new method of sample introduction for carbon furnace atomic emission spectrometry is described. The sample is deposited on a graphite probe which is inserted into the furnace along its length, after the tube has attained its maximum temperature. The heating rate experienced by the sample in an HGA-72 furnace is considerably increased by use of probe atomisation. Improved detection limits for a number of elements are reported, and the interference of magnesium chloride on the emission signals for lead and cadmium is substantially reduced.     

Concurrent solvent recondensation large sample volume splitless injection

Concurrent Solvent Recondensation Large Sample Volume (CRS‐LV) splitless injection overcomes the limitation of the maximum sample volume to 1–2 μL valid for classical splitless injection. It is based on control of the evaporation rate in the vaporizing chamber, utilization of a strong pressure increase in the injector resulting from solvent evaporation, and greatly accelerated transfer of the sample vapors from the injector into the inlet of an uncoated precolumn by recondensation of the solvent. The sample vapors are transferred into the column as rapidly as they are formed in the injector (concurrent transfer). 20–50 μL of liquid sample is injected with liquid band formation. The sample liquid is received by a small packing of deactivated glass wool positioned slightly above the column entrance at the bottom of the vaporizing chamber. Solvent evaporation strongly increases the pressure in the injector (auto pressure surge), provided the septum purge outlet is closed and the accessible volumes around the vaporizing chamber are small, driving the first vapors into the precolumn. Transfer continues to be fast because of recondensation of the solvent, obtained by keeping the oven temperature below the pressure‐corrected solvent boiling point. The uncoated precolumn must have sufficient capacity to retain most of the sample as a liquid. The experimental data show virtually complete absence of discrimination of volatile or high boiling components as well as high reproducibility.