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A commercial 95-% pure boron was ultrasonicated in acetonitrile and then in toluene to remove the surface layer of boron oxide and boric acid. The powder suspended in acetonitrile forms stratified layers, with the bottom layer containing most of the material with the least amount of boron oxide and boric acid. The surface of the processed boron powder was modified with a protective layer, making it more stable in room temperature humid oxidizing environment than the reference 95-% pure commercial boron. The stability of different powders was characterized using isothermal calorimetry employing a thermal activity monitor TAM III with a perfusion ampoule. Oxidation of the surface modified boron powders was studied using thermal gravimetry and compared to oxidation of both 99 and 95-% pure commercial powders. At room temperature, the 99-% pure boron powder was the most stable. Upon heating, the 99-% boron begins oxidizing at a lower temperature than all the 95-% pure powders. However, the apparent activation energy of oxidation at elevated temperatures obtained using a model-free isoconversional methodology for the 95-% pure powder processed in both acetonitrile and toluene is lowest among all tested powders and is close to 100 kJ/mol. It is expected that the latter powder is the most attractive as a fuel, which will be characterized by the shortest ignition delays.

This paper presents results from dynamic calorespirometric measurements on the two mould fungi Penicillium roqueforti and P. camemberti growing on agar. The measurements were made with two isothermal heat conduction calorimeters connected by a tube. In one of the calorimeters, the sample was placed and the other contained a carbon dioxide absorbent. Pressure sensors were connected to both the ampoules. The equipment also contained a valve on the tube that was opened and closed at regular intervals. Measurements were started at normal atmospheric pressure and gas composition, and continued after oxygen was consumed. The response of the fungi to the changing gas composition was followed and gas exchange ratios and metabolic enthalpies were calculated by approximate methods.

The utility of precursors for atomic layer chemical vapour deposition (ALCVD) growth is limited by the sublimation and decomposition temperatures. Sublimation temperatures are conveniently obtained by thermogravimetry (TG) under vacuum. We present here a relatively inexpensive method to obtain information about the decomposition temperature for a precursor candidate for ALCVD. This approach requires an oven with a controlled temperature gradient and a long ampoule for each precursor. The precursors tested in this work comprise the thd complexes (Hthd=2,2,6,6-tetramethylheptane-3,5-dione) of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, La, and Ca.

This paper details the development and application of a novel hydration apparatus, used to initiate water-mediated reactions in an isothermal microcalorimeter. Conventionally, the relative humidity (RH) in a sample ampoule is maintained using one of two methods; an amount of a saturated salt solution is held in a small glass tube (Durham tube or mini-hydrostat) sealed within the ampoule or a carrier gas of known RH is flowed over the sample at a constant rate. The Durham tube method is often used on the basis of simplicity and cost, but has several disadvantages; the system may be rate-limited by the small surface area available for water evaporation, the internal surfaces of the ampoule are wetted and the system cannot reach equilibrium before the reaction is initiated. In this work, we show how by switching the placement of the sample and water reservoir (sample in a sealed hydrostat and water reservoir in the ampoule) many of these drawbacks are overcome. The use of the system is demonstrated by studying the hydration of anhydrous ceftazidime.

Metabolic heat rates of small insects which fit in 1 cm 3 ampoules can be measured readily using the Calorimetry Sciences Corporation 4100 DSC in the isothermal mode. The rapid thermal equilibration of the calorimeter on changing to a new isothermal temperature also permits the response of the metabolism to change in temperature to be determined quickly. By modifying the ampoules and measuring chamber lid for entry of silica capillaries to allow the headspace in the ampoules to be changed in situ, direct comparison can be made of metabolic heat rates in air and in controlled atmospheres. These results aid in assessing the effectiveness of controlled atmospheres, such as low oxygen and/or high carbon dioxide, as potential replacements of methyl bromide for fumigation of fresh produce. For a range of insects tested, including larval, pupal and adult stages, metabolic heat rates decrease to very close to zero under anoxic conditions. By analysis of the headspace of an ampoule containing an insect using ms, changes in metabolic heat rate can be related directly to compositional changes in the headspace, including those resulting from the insect’s metabolism. Important factors in the application of mass spectrometry to the more difficult task of measuring rates of oxygen consumption and carbon dioxide production associated with a metabolic heat rate are discussed.

A recent paper has reported the results of an inter/intralaboratory study into a test and reference reaction for isothermal microcalorimeters, the imidazole catalysed hydrolysis of triacetin. The values derived were 2.8×10 −6 ±9.7×10 −8 dm 3 mol −1 s −1 and −91.7±3 kJ mol −1 for the rate constant and enthalpy, respectively. This paper reports the findings of an investigation, using this test reaction, into the effect of ampoule fill volume on the recovery of the derived rate constant and enthalpy. Fill volume is likely to be of significance for all commercially available, heat conduction, isothermal microcalorimeters. Experiments, reported here, were performed in a thermal activity monitor (TAM, thermometric AB, Jarfalla, Sweden) operating in the batch mode, for 3, 4 and 20 ml glass ampoules and 4 ml stainless steel ampoules. It is shown that the rate constant can be accurately recovered at fill volumes greater than 50% but below 50% fill volume this accuracy diminishes.

Isothermal microcalorimetry gas flow vapour sorption experiments can be used to assess the surface energetics of crystals, the formation and/or loss of hydrates as a function of humidity and the onset of deliquescence, and to identify the presence of amorphous content in powders. These applications require different aspects of calibration. For gas flow instruments, it is simple to calibrate the humidity in the measuring cell by use of a saturated salt solution. To allow the power output to be compared between laboratories, there is a need for a standard test reaction for adsorption behaviour. The use of sealed ampoules containing reservoirs of saturated salt solutions has provided a means by which physical transformations (such as crystallisation) in powders can be followed. The study of crystallisation of amorphous samples involves a complex mixture of exotherms and endotherms which make it difficult to standardise the exact conditions which are used. Comparison of data between different laboratories can therefore become difficult. It is difficult to think of a calibration standard for these type of experiments, as the sample is usually thermodynamically unstable (a physical change is induced during the experiment). The use of water sorption in isothermal microcalorimeters is growing in popularity as a means of characterising both adsorption to and absorption into powders, but there are complex calibration issues that still need to be addressed.

Potato tubers (Solanum tuberosum L. cv. Russet Burbank) were cut into slices 1 mm thick. Tissue was placed in sealed ampules in a calorimeter operated isothermally at 25°C. The metabolic heat rate began to increase within 2 h after slicing, reaching a maximum after 30 h. The peak heat rate was six times that of the initial rate. Heat production was cyanide-sensitive at first while that which developed with time was largely cyanide-insensitive. The initial heat rate per oxygen consumed increased to a peak value, indicating greatly reduced energy conservation. The ratio of CO2 produced to O2 consumed, together with the CO2 rate/heat rate indicated a change from more reduced to more oxidized substrates, i.e. from lipid to starch. Calorimetric results were in good agreement with published results obtained with other methods.

A new device for thermal vapor-pressure shock explosion (TSE) was constructed and the dispersion of three kaolinites (KGa-1, KGa-2 and S-5, well and poorly crystallized kaolinites from Georgia, USA and from Makhtesh Ramon, Israel, respectively) in aqueous suspensions investigated. In the new device, the clay suspension is heated in a sealed glass ampoule at 300°C for a few minutes and the water vapor pressure increases in the cell to ≈100 atm. At this stage the ampoule is shattered in ice-cold water. This treatment stabilized suspensions of KGa-1 and S-5 kaolinites. Particle-size distribution analysis showed that, by this treatment, smaller particles were obtained. A suspension of KGa-2 was not stabilized by this treatment although particles became smaller. Suspensions of the three kaolinites peptized by sodium pyrophosphate, were compared with those obtained by TSE treatment. SEM images and XRD patterns of sedimented films showed that tactoids became thinner as a result of the TSE treatment. EDS analysis of Ti suggested that the small particles, after the TSE treatment were formed from the disaggregation of the large aggregates.

152 biopsies from the colon of healthy persons were incubated with several nutrition mediums in a microcalorimeter. The course of the heat-flow rate was measured at 1 min interval and graphically displayed as a function of time. For evaluation of the results, the maximum ( P max ), the mean values ( P ), and the area under the curve as a measure of the total released energy ( E tot ) of the power-time curves were determined. The mean enthalpy change of all samples over time was 3.9 μW per sample. Depending on incubation conditions, mean values ranged between 2.5 and 7.1 μW, maximal values between 3.5 and 13.3 μW. The areas under the curve varied between 6.2 and 18.3 mJ. Our results also showed that bacterial growth can influence measured enthalpy changes if antibiotics are not present. Under identical incubation conditions, steel ampoules were better than glass ampoules with respect to methodic artifacts. We conclude that microcalorimetric investigations on bioptic material from colonic epithelium are possible. Interestingly, our measured enthalpy changes were lower than those expected from the oxygen consumption rates and other metabolic processes. The reason is yet to be explored.

Methods and equipment are described for simultaneous measurements of heat flow rates, CO 2 evolution rates, O 2 use rates and sample volumes for three samples in a differential heat conduction calorimeter. Isothermal measurements of metabolic heat rates were conducted in 1 ml sealed ampoules connected to pressure sensors. Pressure measurements in the presence and absence of a CO 2 trapping solution allow determination of the gas flux rates. The decrease in the partial pressure of O 2 within the sealed ampoule under trapping conditions measures O 2 consumption by the tissue. The CO 2 rates are determined by two methods. Absorption of CO 2 produces heat at a rate proportional to the rate of CO 2 production. Also, the difference between the rate of change of pressure with and without trapping solution yields the CO 2 production rate by the tissue. Measuring gas flux by pressure change requires knowledge of headspace volume. Two methods of headspace volume determination are discussed. The first involves the introduction of a mass of known volume into the ampoule during pressure change measurements and the second involves recording the pressure increase upon addition of a known volume of gas into the ampoule. The methods described here are useful for studies of metabolic efficiency in biomass production and examination of responses of cell metabolism to changes in environmental or physiological conditions.

Cellular thermogenesis in L-929 mouse fibroblasts growing in glass ampoules was monitored over 72 h in three different systems: (1) closed ampoules with 2.5 ml of control medium; (2) closed ampoules with 2.85 ml of medium and a reduced oxygen content; and (3) ampoules kept open. Thermogenesis was determined as heat production (HP) and the pH, and oxygen, glucose and lactate contents in the medium as well as the cellular growth were assessed in order to evaluate whether small gaseous volumes are sufficient to facilitate adequate oxygen supply. Oxygen deficiency resulted in lower HP, decreased growth and enhanced anaerobic rate of glycolysis. Low gas volume was associated with decreased HP after 40 h and a steady increasing rate of aerobic glycolysis similar to that shown during O 2 deficiency. In the open system a more pronounced decrease of HP was observed.

Heat loss and respiration following amendment with glucose were recorded for soils contaminated with heavy metals and organic pesticides over a period up to 28 days. For this purpose, measuring ampoules were adapted to enable measurement of heat loss and CO 2 evolution on the same soil sample and at the same time. Heat loss and CO 2 evolution were highly correlated ( r 2 = 0.83), which is explained by the fact that in our studies heat loss from soils could be almost entirely attributed to metabolic reactions transforming glucose into CO 2 . These results demonstrate that the described adapted ampoules can be useful instruments to monitor microbial activity both accurately and economically by heat loss and CO 2 production on the same soil samples during decomposition of various C substrates.

The molar enthalpies of mixing ΔmixHm in the liquid NaClNdCl3, KClNdCl3, RbClNdCl3 and CsClNdCl3 binary systems have been measured over the whole composition range at 1124, 1065, 1122 and 1122 K, respectively, with an accuracy of about 6%. The apparatus used was a Calvet-type high-temperature microcalorimeter and mixing of the two liquid components was obtained by the break-off ampoule technique. In the investigated systems, the enthalpies of mixing are negative with minimum values at about −5.7, −16.6, −20.2 and −23.4 kJ mol−1, respectively, at χNdCl3 = 0.4. These values are almost identical, within the experimental accuracy, to those in other previously investigated MClLnCl3 mixtures. The molar enthalpies of formation ΔfHm(K3NdCl6, 1, 1065)/kJ mol−1, ΔfHm(Rb3NdCl6, 1, 1122)/kJ mol−1 and ΔfHm(Cs3NdCl6, 1, 1122)/kJ mol−1, according to the reaction 3 MCI(1) + LnCl3(1)= M3LnCl6(1), are equal to −55.2, −68.8 and −80.8 kJ mol−1, respectively. The least-squares coefficients A, B, C, D, E of the equation for the interaction parameter λ= A + Bχ + Cχ2 + Dχ3 + Eχ4χ4 (in kJ mol−1) are presented.

The molar enthalpies of mixing Δ mix H m in the PrCl 3 CaCl 2 and NdCl 3 CaCl 2 liquid binary systems were measured at 1073 K over the whole composition range under argon at atmospheric pressure. The apparatus used was a Calvet-type high-temperature micro-calorimeter and mixing of the two liquid components was obtained by the break-off ampoule technique. In both systems the plots of enthalpies of mixing versus composition were “S-shaped” curves. The enthalpy of mixing values are positive for NdCl 3 - and PrCl 3 -rich compositions, and negative for other compositions. These values are very small (from about −200 to about 180 J mol −1 ). In the PrCl 3 CaCl 2 and NdCl 3 CaCl 2 liquid binary systems,Δ mix H m ≈0 at χ PrCl 3 ≈ 0.6 and at χ NdCl 3 ≈ 0.4, respectively. These results are discussed in terms of equilibrium between the LnCl 3 (where Ln is Pr, Nd) polymers and anionic complexes as a function of the composition of the melts.

A thermal method to investigate decomposition reactions in a self-generated atmosphere is proposed. A sample having 3–70 mg mass was charged through a branch pipe into an ampoule which was a cylinder with 10 mm height and 0,9 ml volume. Such stainless steel ampoules could bear internal pressure up to 15 MPa. Before the experiment the ampoule branch pipe was sealed in the air or in an inert gas medium. Sizes and the design of the ampoule allowed to conduct investigations using a triple heat bridge dynamic calorimeter, designed before (ref.1). We studied a wide range of substances decomposed with the formation of gaseous products. As an example we provide brief results of investigation of ammonium carbamate and copper formate.

When studying crytalline substances and liquids in sealed off glass ampoules by differential thermal analysis the melting ranges but not the heat of evaporation of the liquids and fused substances are found, because inside the glass ampoule, there will always be the vapour pressure equillibrium which corresponds to the temperature. With liquids undergoing decomposition, it is possible to measure the range and heat of decomposition. Given a suitable quantity inside the ampoule the critical temperature, e.g., of water of ethanol can be measured for non-decomposing liquids. The measuring effect is based on the pronounced change of the liquid's specific heat at the critical temperature. Fundamental studies of the measurement of critical temperatures of liquids were carried out by the turn of the century. One the methods reported is the meniscus method, optimal measurement of the critical temperature, which comprises a liquid being filled into a glass tube which is then sealed by melting. The glass tube is heated while observing the meniscus. Its rise means that the critical volume has been exceeded, while a drop means that it has not yet been reached. The conditions are only met when that volume of liquid has been filled into the tube at which the meniscus neither rises nor falls on heating but rather remains, e.g. at mid level of the tube until it disappears. The tube contains the critical volume at the critical density when the critical temperature is reached. The critical pressure is then present. These conditions are obtained when the meniscus disappears and the liquid completely goes over into the vapour phase. The melting range (and the latent heat of fusion) are found when investigating a crystalline material under normal pressure by differential thermal analysis. Given a suitable arrangement the boiling temperature and, in rough approximation, the heat of evaporation are also found (Fig.1). The latent heat of fusion is found again when carrying out the same measurement in a closed system (glass tube sealed by melting). The heat of evaporation can no longer be measured since the vapour pressure equilibrium coresponding to the given temperature is present in the glass tube.

Chemical reactions involving volatilizable substances cannot usually be studied by standard DTA or DSC techniques. However, such difficulties can be overcome by using sealed sample containers as micro-reactors. This work describes the adaptation of a sealed ampoule technique to standard commercial equipment for calorimetric studies of several chemical reactions. The reaction products are then analyzed by other instrumental techniques such as gas chromatography, mass spectrometry, or infrared spectroscopy.

A sample container system was developed, which consists of a sealed micro-ampoule as the sample pressure vessel and a special ampoule cradle designed to optimize heat detection efficiency, reproducibility, baseline stability, and thermal responses. The heat detection efficiency and thermal responses of the sample container system were determined and compared to those of others. The reproducibility of heat measurements has been assessed using several common thermal standards and other chemicals. The interpretation of heat measurements by differential scanning calorimetry is also discussed.

A specially designed capillary tube and tube holder have been developed for thermal hazard evaluation using differential scanning calorimetry. This capillary tube container has several important advantages compared to other common sample encapsulation approaches. The glass container is inert to most materials and is capable of withstanding pressures in excess of 21 MPa (3000 psi) and temperatures up to 500 °C. The vaporization effect, often present in scanning calorimetry of fluids to high temperatures, will be negligible in most analyses because high sample volume to total volume ratios are possible. The device gives a stable baseline and provides better temperature resolution than do previous glass ampoule devices. The onset temperature and the enthalpy of fusion of indium have been measured with 95% confidence intervals of 2.1°C and 1.1%, respectively. The calorimetric response of the device is linear for indium fusion between 0.6 and 14 mg of sample. The heat of thermal decomposion of a solution of AIBN in methylene chloride was determined to be 277 ± 7 J g− with a peak temperature of 124.2 ± 0.8 °C at the 95% confidence level.