Reply to “Comment on papers by K. Shanahan that propose to explain anomalous heat generated by cold fusion”, E. Storms, Thermochim. Acta, 2006

Dr. E. Storms has published a Letter [E. Storms, Comment on papers by K. Shanahan that propose to explain anomalous heat generated by cold fusion, Thermochim. Acta, 2006] in which he argues that in a sequence of recent papers, the apparent excess heat signal claimed by Dr. Shanahan to arise from a calibration constant shift is actually true excess heat. In particular he proposes that the mechanisms proposed that foster the proposed calibration constant shifts cannot occur as postulated for several reasons. As well, he proposes Shanahan has ignored the extant data proving this. Because this Letter may lend unwarranted support to acceptance of cold fusion claims, these erroneous arguments used by Storms need to be answered.     

Determination of Michaelis-Menten parameters obtained from isothermal flow calorimetric data

Recent papers have reported [Thermochim. Acta 399 (2003) 63; Thermochim. Acta, in press] the results of a preliminary inter/intra laboratory study into the suitability of the base-catalysed hydrolysis of methyl paraben as a test and reference reaction for isothermal flow-through calorimeters. It was shown that this reaction can be used to investigate the flow characteristics of the instrument being used. It has also allowed, for the first time, the calculation of accurate values for the rate constant and for the enthalpy change, ΔH (hereafter H (enthalpy) for simplicity) of reaction directly from the calorimetric data, free from assumption. These findings have been extended to permit the direct determination of Michaelis-Menten based kinetic parameters from calorimetric data again free from assumption (except that the system conforms to Michaelis-Menten kinetic theory). This paper describes the method used for such an analysis and reports the results of a preliminary study on the urea/urease enzymatic system.     

Comments on “The use of MoO3 and NiO (pure or mixed) oxide catalysts in the decomposition of KMnO4” by S.A. Halawy and M.A. Mohamed

The recent paper by Halawy and Mohamed [S.A. Halawy, M.A. Mohamed, Thermochim. Acta 345 (2000) 157] has raised several problems which need to be resolved. Our comments are given under the headings of the sections of the original paper.     

Molecular symmetry depresses the entropy of fusion of organic molecules with regard to their expected values when comparing structural isomers

Using published data, the symmetry effect on the entropy of fusion, ΔS_f, of rigid organic molecules has been investigated by comparing structural isomers. Because ΔS_f is dependent on the enthalpy of fusion, ΔH_f, [A.S. Gilbert, Thermochim. Acta 339 (1999) 131-142] this dependence must be allowed for as ΔH_f values can vary quite widely. When this is done, it is found that more symmetric isomers usually have lower than expected values of ΔS_f, in relation to ΔH_f, than their less symmetric counterparts. This is the reason that more symmetric isomers generally melt at higher temperatures, a fact noted by many workers over the years.     

Melting of polycaprolactam

Highly crystalline polycaprolactam was prepared by zone polymerization of ε-caprolactam. Folded-chain crystallized and annealed, melt-crystallized, and solution-crystallized polycaprolactam was produced from commercial polycaprolactam. All samples were characterized by x-ray diffraction, electron microscopy, density measurement, and heat of fusion measurement. The determination of the time-dependent melting by DTA and scanning calorimetry revealed that all the different morphologies show different melting behavior. Zone-polymerized polycaprolactam superheats, and the other morphologies reorganize on heating to different degrees. Densities and heat of fusion vary in the same manner—from highest to lowest—in the order: zone-polymerized, solution-crystallized, annealed, and melt-crystallized. An estimate of heat of fusion, equilibrium melting point, and surface free energy was obtained from the melting points.     

硝酸肼的量热研究

用精密自动绝热量热计测定了在220 K—370 K温度范围内硝酸肼的热容、熔化热、熔化温度和熔化熵。所得热容数据的精密度以百分偏差的均方根值表示为±0.2％。三次熔化热测定的相对偏差为±0.1％。为验证结果的可靠性, 用该装置测定了冰的熔化热和熔化温度, 其结果与文献值一致; 又用法国SETARAM公司的高温量热计测定了硝酸肼的熔化热和熔化温度, 其结果与我们用量热法测定的结果一致; 从量热结果计算出了该试样的纯度, 该结果亦与化学分析的结果一致。这些均可说明我们所测得的数据是可靠的。     

Critical temperature measurements of liquids by means of differential thermal analysis

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.     

Determination of ice content in hardened concrete by low-temperature calorimetry

Low-temperature calorimetry has been used to determine the ice content in concrete at different temperatures when exposed to low-temperature environments. However, the analysis of the ice content from the measured data of heat flow is not straightforward. In this study, two important factors influencing the ice content calculation are discussed. The importance of the baseline determination for the calculation of the ice content is realized. Two different methods of generating the baseline are discussed. First, the ‘J-baseline’ is discussed which is a recently proposed extrapolation method based on the accumulated heat curves measured in the freezing and the melting process. Second, the ‘C-baseline’ is discussed in which a calculated baseline is used where the heat capacity of both water and ice and the phase changing behaviour under different testing temperatures are considered. It turns out that both the ‘J-baseline’ method and the ‘C-baseline’ method can be used to calculate the approximate baseline. The heat of fusion of the water confined in small pores is another important parameter to be considered in ice content calculation. This property must be carefully analyzed in order to accurately calculate the ice contents at different temperatures in the freezing and melting process. It should be noted that there is no general agreement on how to obtain the important temperature dependence of the heat of fusion of water confined in small pores. By performing comparison studies, the present study shows the influence of the different values of the heat of fusion commonly adopted on the calculated ice content for the studied concrete samples. The importance and necessity to use an accurate value of the heat of fusion is emphasized. Based on the calculation of the baseline proposed in this work and by carefully selecting the values for the heat of fusion, the ice content in a hardened concrete sample is expected to be estimated with an acceptable accuracy.     

Study on thermal properties of TBAB–THF hydrate mixture for cold storage by DSC

In order to study the thermal properties of new type environment-friendly binary hydrate for cold storage in air-conditioning system, tests have been carried out by DSC comprehensively on the phase-change temperature and fusion heat of TBAB hydrate, THF hydrate, and TBAB–THF hydrate mixture. The results show a good trend that TBAB–THF hydrate has the superiority for more proper phase-change temperature and increased fusion heat. A broader and more developed view is that adding appropriate amount of hydrate with lower phase-change temperature to hydrate with higher one can make the hydrate mixture more suitable for cold storage (especially for 278–281 K); some hydrates with lower phase-change temperature can even make the fusion heat of mixture hydrate increased greatly. Several new environmental working pairs for binary gas hydrates have been listed to help to promote the application.     

QCM/HCC as a platform for detecting the binding of warfarin to an immobilized film of human serum albumin

Quartz crystal microbalance/heat conduction calorimetry (QCM/HCC) is a new measurement technology that has been used to monitor simultaneously the mass and motional resistance of a thin film in conjunction with the heat flow produced by a chemical change in the film initiated by reaction with a gas. In this work we examine the applicability of the QCM/HCC in detecting chemical changes at the solution/thin film interface. Human serum albumin (HSA) was bound to the gold electrode of a 5 MHz AT-cut quartz resonator using three types of linkers and then exposed to buffered solutions of the anticoagulant drug warfarin. Changes in resonator frequency and motional resistance as well as changes in heat flow produced by warfarin binding to HSA were monitored as a function of the warfarin concentration. Differences in frequency and motional resistance changes depend upon the linker and vary both in magnitude and sign, whereas the integrated heat signal is proportional to the concentration of warfarin and independent of the linker chemistry. Quartz crystal microbalance/heat conduction calorimetry can thus be a useful tool for studying protein-ligand interactions at the solution-surface interface, even though the quartz resonator does not behave as a microbalance.     

The rectified second law of thermodynamics

Equilibrium thermodynamics is combined with Jarzynski's irreversible work theorem to quantify the excess entropy produced by irreversible processes. The resulting rectified form of the second law parallels the first law, in the sense that it facilitates the experimental measurement of excess entropy changes resulting from irreversible work and heat exchanges, just as the first law quantifies energy changes produced by either reversible or irreversible work and heat exchanges. The general form of the rectified second law is further applied to a broad class of quasi-static irreverisble (QSI) processes, for which all of the thermodynamic functions of both the system and surroundings remain continuously well-defined, thus facilitating excess entropy measurements by integrating exact differential functions along QSI paths. The results are illustrated by calculating the mechanical and thermal excess entropy produced by the irreversible unfolding of an RNA molecule.     

Melting behavior of drawn films from polyethylene single-crystal mats

Drawing of mats of linear polyethylene single crystals prepared from dilute solution is possible at temperatures above about 90°C. The structure and properties of the drawn specimens are much different from those ordinary drawn bulk polymer. Drawn mats have been investigated by differential scanning calorimetry. The characteristic experimental results are: (a) a broad melting curve, (b) considerable superheating depending on the rate of heating, (c) constancy of the melting point and the heat of fusion with annealing, (d) deviation from the relation between the heat of fusion and the density obtained for the drawn bulk specimens, (e) appearance of two melting peaks in samples annealed at temperatures above about 130°C. These results imply that the structure of the drawn mat is characterized by a larger number of the tie chains connecting the neighboring crystals (the structure postulated in earlier papers) than is the case in ordinary drawn bulk polymer. It can be concluded that the transformation of a fringed micellar type of structure to the folded lamellar structure may be difficult during annealing unless crystals melt and then recrystallize during cooling.     

Description of the shape of thermoanalytical curves

Empirical parameters were chosen for the characterization of peaks (or steps) of thermoanalytical curves. The parameters were applied in studies on the repeatability, the relationship between kinetic constants and peak shape, the effect of sample thermal resistance. Kinetic constants can be estimated on the basis of peak shape parameters. Besides, approximate criteria were formulated for experiments allowing kinetic evaluation with the neglect of the heat transport within the sample. The empirical parameters were also used in checking the suitability of DSC data for purity analysis and in detecting changes of the thermal decomposition of papers caused by ageing.Zur Beschreibung von Peaks bzw. Stufen thermoanalytischer Kurven wurden emperische Parameter ermittelt, die bei der Untersuchung der Reproduziertbarkeit, der Beziehung zwischen kinetischen Konstanten und Peakform so wie des Einflusses des thermischen Wiederstandes der Probe angewendet wurden. Kinetische Konstanten können auf der Basis von Peakformparametern geschÄtzt werden. Weiterhin wurden Kriterien für Experimente ermittelt, die eine kinetische NÄherungslösung unter VernachlÄssigung des WÄrmetransportes innerhalb der Probe ermöglichen. Die empirischen Parameter wurden au\erdem bei der Untersuchung der Eignung von DSC-daten zur Reinheitsanalyse angewendet, weiterhin zum Nachweis von alterungsbedingten Änderungen der thermischen Zerzetzung von Papier.

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The authors express their thanks to Mrs E. Tóth for her valuable technical help. The permission to reproduce Figs 2–6 and 8–10 from Analytica Chimica Acta and Thermochimica Acta (Elsevier, Amsterdam) is also acknowledged.     

Thermal characterization of poly-l-lactide by dielectric analysis and modulated DSC

Dielectric analysis (DEA) is a very sensitive technique, which allows for detection of small structural changes at the low scale. An advantage of DEA, with respect to other modulated techniques, is the possibility of using a wider frequency range. Molecular relaxations of the order of only a few nanometers are not observed by any other thermoanalytic method. Nevertheless, these small relaxations involve dipole changes that can be observed by DEA. Thus, this technique is used here, in combination with temperature-modulated differential scanning calorimetry (TMDSC) to obtain insightful information about the thermal transitions of poly-l-lactic acid (PLLA), one of the stereo-isomers of polylactide. Its complex thermal behavior is the subject of ongoing debate, with several overlapping crystallization and melting processes. The combined use of TMDSC and DEA provides a better insight of three important transitions of this polymer: the alpha relaxation, the enthalpic relaxation, and the cold crystallization. The dependences of the enthalpy relaxation on the dynamic glass transition relaxation and on the glass transition as a thermal event are evaluated. On the other hand, it will be shown how the cold crystallization can be identified by TMDSC, and DEA helps us understand the effect of crystallization on the dipole movements. The shape of the dielectric permittivity curve at low frequencies is compared to that of the reversing heat capacity to check whether both signals are sensitive or not to the same events. It is also verified how the experimental results of alpha relaxation of PLLA follow an Arrhenius or a Vogel trend.     

Chemical speciation by flow-injection analysis. A review

Speciation of elements in natural matrices, especially of trace metals, is one of the predominant development trends of modern inorganic analysis. The main part of the conventional speciation procedures is a suitable combination of separation and chemical conversion steps, for which the most appropriate methodology seems to be the use of flow-injection. A shorter time of performance of these operations in flow-injection manifolds is advantageous in terms of avoiding the shift of chemical equilibria during the speciation measurement. Numerous other advantages are also pointed out in this review based on 58 references. Among flow-injection analysis methods published so far for speciation the determination of different oxidation states predominates, while a much smaller number of papers have been published on the determination of the degree of complexation or the determination of organometallic compounds.     

Preface

Welcome to the Reader! You, the reader, hold in your hands a valuable journal issue that contains a number of thermal analysis papers that were presented at the 32nd annual meeting of the North American Thermal Analysis Society (NATAS). This conference was held in Williamsburg, Virginia, USA from the October 4 to 6, 2004. NATAS is known of its dedication in promoting the understanding and advancement of thermal analysis. NATAS is the largest national thermal analysis society in the world, and over its more than 30 year existence, it has represented the interests of numerous scientists, technicians and engineers, as well as major instrument vendors functioning in the area of thermal analysis. NATAS is an affiliate of the International Confederation for Thermal Analysis and Calorimetry (ICTAC), and has been co-operating with ASTM (American Society for Testing and Materials) for a long time especially Committee E37 on Thermal Measurements. The Short Course in Thermal Analysis held right before the conference, provide excellent educational opportunities for technical people, both experienced in the use of thermal analysis and those expanding their skills to learn thermal analysis. In this year's program, by our count, 225 papers were presented in nineteen different sessions (Kinetics; Fast Scan DSC; Semicrystalline Polymers; Thermal Conductivity; Pharmaceuticals; Poster Session; Educational Applications; Thermoplastic Polymers; Combined and Hyphenated Techniques; Composites, Nanocomposites and Thermosets; Thermal Hazards/Energetic Materials; Wood Materials; Rheology; Foods; Professional Enhancement; General Session; Flame Retardancy; Films and Fibers; Medical Polymers). Although thermal analysis is present in all areas of chemistry, the just described list of 2004 NATAS sessions clearly indicates that polymers still represent the majority among the materials tested by thermal analysis, or at least by the NATAS membership. Another phenomenon that may be seen when comparing these papers with earlier NATAS issues is some structural change in the type of the papers. As the chemical industry is inevitably being transformed in the era of globalization, it also affects thermal analysis. The emphasis is shifted from theoretical papers more to applications of thermal analysis. This special issue contains selected papers from the 2004 Annual NATAS Meeting. Another group of selected papers will be published in Thermochimica Acta. You may be surprised to see the NATAS material collected in two special issues of the two thermal analysis journals. However, NATAS has now decided it is time to return to the good old times and publish together the selected papers presented at its annual meeting. This year was a trial year of how the best NATAS papers should be presented to the world. The 2005 NATAS papers will be published in one special issue of Journal of Thermal Analysis and Calorimetry. At the annual NATAS meetings, in addition to the classical conference, there is always an instrument exhibition of a considerable size. The most important instrument manufacturers of the world are always present at this exhibition. In addition of being present, they provide funding to NATAS through financing some of the essential needs of the conference. Thus, we sincerely thank the following NATAS conference sponsors for their support: TA Instruments, PerkinElmer Life and Analytical Sciences and Mettler-Toledo. We are also thankful to both symposia sponsors: ExxonMobil Chemical Company and Abbott Laboratories. We hope the excellent relationship between NATAS and its corporate sponsors, and the instrument vendors is permanent. Above all, we thank all the authors and reviewers for their valuable contribution, because we feel that re-starting of regular publishing of the papers of the annual NATAS meetings is extremely important. We express our gratitude to the editorial offices of both Journal of Thermal Analysis and Calorimetry, and Thermochimica Acta for providing the opportunity to publish these papers.     

The thermal stability of fully charged and discharged LiCoO2 cathode and graphite anode in nitrogen and air atmospheres

Polyethylene glycol (PEG) compounds and mixtures have many properties that make them suitable for thermal applications in buildings, such as having high heat of fusion, phase change repeatability, chemical stability, non-corrosive behavior, and low-cost. In this study, we developed a number of PU rigid foams incorporated with three types of PEGs, as new insulation materials provided with an enhanced thermal capacity, and sought their suitability for various applications such as layer of floor and ceiling coverings in constructions, insulations in controlled temperature transportation packaging, inner coverings of automobile seats, etc. In order to investigate the thermal properties of PEG-containing PU foams, differential scanning calorimeter (DSC) tests were conducted first. Then, a two-layer concrete–PU foam system was designed in the laboratory conditions to examine the insulation performances via using a computer-aided thermal measurement setup which was sensitive to the simulated environmental temperature changes. The PU-PEG composites produced here can be helpful for the design of thermal insulators. PUI, including 44% PEG 600, exhibited fairly efficient thermal regulation under moderate ambient temperature conditions, whereas PUII (49% PEG 1000) is suitable for temperature control in both mild and hot surroundings. PUIII, containing 53% PEG 1500, showed suitable heat storage and thermal stability characteristics. PUIV, containing 38% PEG 600/PEG 1000/PEG 1500, also confirmed good thermal and durability characteristics. The blend of three PEGs is suitable for preventing discontinuous thermal regulation when the external temperature increases or decreases. PU foams containing PEGs can be assumed to be leak-resistant, which is promising for their industrial applications.     

Measurement of the enthalpies of vaporization and sublimation of solids aromatic hydrocarbons by differential scanning calorimetry

An experimental procedure is proposed for direct measurement of the heat involved in the vaporization of a solid organic compound above its normal melting temperature. This technique consists on the fusion of a solid aromatic hydrocarbon, which is then vaporized by a sudden decrease of the pressure. The direct register of heat flow as function of time by differential scanning calorimetry allows the quantifying of the enthalpy of vaporization of compounds such as phenanthrene, β-naphthol, pyrene, and anthracene. Enthalpies of vaporization were measured in an isothermal mode over a range of temperatures from 10 to 20 K above the melting temperatures of each compound, while enthalpies of fusion were determined from separate experiments performed in a scanning mode. Enthalpies of sublimation are computed from results of fusion and vaporization, and then compared with results from the literature, which currently are obtained by calorimetric or indirect techniques.     

The pre‐separation of oxygen containing compounds in oxidised heavy paraffinic fractions and their identification by GC‐MS with supersonic molecular beams.

The heavy petroleum fractions produced during refining processes need to be upgraded to useable products to increase their value. Hydrogenated heavy paraffinic fractions can be oxidised to produce high value products that contain a variety of oxygenates. These heavy oxygenated paraffinic fractions need to be characterised to enable the control of oxidation processes and to understand product properties. The accurate identification of the oxygenates present in these fractions by electron ionisation (EI) mass spectrometry is challenging due to the complexity of these heavy fractions. Adding to this challenge is the limited applicability of EI mass spectral libraries due to the absence of molecular ions from the EI mass spectra of many oxygenates. The separation of oxygenates from the complex hydrocarbon matrix prior to high temperature GC‐MS (HT‐GC‐MS) analysis reduces the complexity of these fractions and assists in the accurate identification of these oxygenates. Solid phase extraction (SPE) and supercritical fluid chromatography (SFC) were employed as prefractionation techniques. GC‐MS with supersonic molecular beams (SMBs) (also named GC‐MS with cold‐EI) utilises a SMB interface with which EI is done with vibrationally cold sample compounds in a fly‐through ion source (cold‐EI) resulting in a substantial increase in the molecular ion signal intensity in the mass spectrum. This greatly enhances the accurate identification of the oxygenates in these fractions. This study investigated the ionisation behaviour of oxygenated compounds using cold‐EI. The prefractionation by SPE and SFC and the subsequent analysis with GC‐MS with cold‐EI were applied to an oxygenated heavy paraffinic fraction.