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  • 1
    ISSN: 1435-2451
    Keywords: Fracture of the vertebral column ; Spinal CT scan ; Wirbelfrakturen ; Spinales Computertomogramm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Im Beobachtungszeitraum vom 1. 1. 1982 bis 31. 12. 1982 wurden 34 Patienten mit 44 frischen Wirbelverletzungen einer Diagnostik durch konventionelle Röntgenaufnahmen und durch Computertomographie unterzogen. Frakturen der Wirbelkörperhinterkanten, Einengung des Spinalkanals durch Knochenfragmente, Brüche der Wirbelbögen, der Gelenkfortsätze, der Quertfortsätze und der Dornfortsätze konnten computertomographisch insgesamt 47mal (100%) nachgewiesen werden; die Diagnose der selben Verletzungen war mit konventioneller Technik nur 15mal (32 %) möglich. Der Informationsgewinn durch das CT betrug demnach 68 %. In 6 Fällen wurden erst durch das CT instabile Frakturen erkannt, in einem Fall ausgeschlossen; der Therapieplan wurde aufgrund der CT-Befunde in 7 Fällen (20,5 %) geändert.
    Notes: Summary The authors give an account of 34 patients with 44 fresh fractures of the spine, diagnosed by conventional X-ray examination and computed tomography (observation period 1. 1. 1982 to 31. 12. 1982). Fractures of the posterior aspect of the vertebral body, narrowing of the vertebral canal by bone fragments, fractures of vertebral arches as well as of transverse and spinous processes were diagnosed 47 times (= 100 %) by computed tomography, whereas conventional X-ray offered the same diagnosis in only 15 cases (32 %). The diagnostic information via CT-scan therefore showed an increase of 68 %. In only 6 cases did spinal CT reveal an instable fracture of the vertebrae, in one case suspected instability was ruled out. In 7 patients (20.5 %) the therapeutic schedule was changed due to additional information obtained by CT.
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Specific heat measurements have been performed on single crystals of Y1−xPrxBa2Cu3O1−δ (x=0.33, 1) in the temperature range 2 K〈T〈50 K with magnetic fields up to 7.5 T, both parallel and perpendicular to the c-axis. The crystals were grown in BaZrO3 crucibles and therefore the possibility of crucible contamination in the crystals is reduced to a large extent. A large linear term with γ=207 mJ/mol K2 was determined for x=1 and the crystal field contribution due to Pr ion was calculated for both the samples. The transitions were found to be sharp lambda type for x=1 with the ordering temperature at 16.6 K and very broad for x=0.33 with the transition temperature below 2 K. Also, the transition temperatures increased for x=0.33 and decreased for x=1 with increasing magnetic fields indicating a different type of interaction for these two samples. The coupling in the ab plane was found to be stronger than in the c-axis. © 1997 American Institute of Physics.
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Crystal electric field (CEF) effects are of essential importance for the magnetic properties of rare-earth ions. For NdBa2Cu3Ox the variation of the CEF due to a reduction of oxygen directly influences the character of the magnetic ordering and partially explains the peculiar magnetic behavior of this system: Oxygen reduction transforms the 2D-Ising system just below x=6.9 into a (short-range) 2D-Heisenberg system due to a reduction of the single-ion anisotropy. Since, magnetic specific heat data for Ga-doped NdBa2Cu3Ox resemble very much the oxygen reduced data, neutron CEF spectroscopy of Nd3+ in NdBa2(Cu3−yGay)Ox was performed to deduce the behavior of the single-ion anisotropy. These neutron data in conjunction with paramagnetic susceptibility and specific heat data confirm the strong influence of the CEF on the magnetic ordering of the Nd ions. © 1996 American Institute of Physics.
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  • 4
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic susceptibility of Ho2Mn2O7 with a spontaneous rise below about 40 K and a paramagnetic Curie temperature of +39 K suggests a ferromagnetic ordering. Indeed neutron diffraction profiles show strongly enhanced Bragg peaks with a temperature dependence which indicates an apparent Tc≈35 K. Nonetheless, the magnetic diffraction pattern is not consistent with a collinear ferro or ferrimagnetic ordering of the Ho3+ and Mn4+ sublattices. Furthermore, specific heat and small angle neutron scattering (SANS) show features which are also incompatible with conventional long-range order. © 1996 American Institute of Physics.
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  • 5
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper outlines the design characteristics of a combined cryostat/furnace set‐up dedicated to high‐pressure μSR experiments using a cylindrical high‐pressure cell made of the high‐strength titanium alloy Ti‐6Al‐4V‐ELI. This set‐up provides the possibility to perform μSR measurements on samples with diameter of 12 mm and length of 35 mm in the temperature regime 3.7\Eleq T\Eleq 800\ K at hydrostatic pressures up to 800 MPa. Results for high‐pressure μSR experiments on Ni and \alpha ‐Fe are presented.
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  • 6
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Konstruktion und Betrieb eines neuen vollautomatischen Mikrokalorimeters werden beschrieben. Mit dem Instrument können Messungen von spezifischen Wärmen an kleinen Proben im 10-mg-Bereich bei tiefen Temperaturen (10 K 〈T 〈 350 K) durchgeführt werden. Mit der neuen Methode werden die nichtadiabatische Relaxationskalorimetrie mit der Zwillingsanordnung und gleichzeitigem Temperaturscanning kombiniert. Das Meßsystem des Kalorimeters mit der Probenhalterung wird genauer vorgestellt. Die Genauigkeit des Kalorimeters wird durch Eichmessungen mit einer Kupferprobe (56 mg) geprüft. Nahe 12 K wurde eine Auflösung von 0.1μJ K−1 erzielt. Die Zuverlässigkeit des Mikrokalorimeters wird an einer Bestimmung der spezifischen Wärme des neuen Supraleiters YBa2Cu3O7−y demonstriert.
    Abstract: РЕЗЮМЕ Описана конструкция и принцип действия но вого полностью автоматиз ированного микрокалориметра. Пр ибор позволяет прово дить измерения удельной т еплоемкости с малым количеством образца (около 10 мг) при низких температурах в интер вале 10 К 〈 Т 〈 350 К. Метод состоит в комби нировании неадиабат ического время-релаксационно го калориметра с двойным расположени ем и с одновременным и змерением температуры. Предста влены некоторые экспериментальные д етали калориметра и д ержателей образцов. Точность ка лориметра была прове рена калибровочными изме рениями 56 мг меди. Разр ешение по энергии составляло 0,1 м кдж/К и было достигнуто при температуре около 12 К. С целью показа надежности ми крокалориметра была определена тепл оемкость новогоТ C сверхпроводника YBa2Cu3O7-y .
    Notes: Abstract The construction and operation of a new fully automated microcalorimeter is described.This instrument allows specific heat measurements to be performed on small samples in the 10 mg-range at low temperatures (10 K 〈T 〈 350 K). The new method consists of ombining the non-adiabatic relaxation-time calorimetry with a twin arrangement and simultaneous temperature scanning. Some experimental details of the calorimeter and sample holders are presented. The accuracy of the calorimeter was verified by calibration measurements on 56 mg of copper. An energy resolution of 0.1μJ/K has been reached near 12 K. To demonstrate the reliability of the microcalorimeter the heat capacity of the new highT c superconductor YBa2Cu3O7−y, was determined.
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  • 7
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die spezifischen Wärmen derCluster-Verbindungen [Ag6M4P12]Ge6 (M=Ge, Sn) wurden im Temperaturbereich 2 K bis 300 K bestimmt. Die thermische Zersetzung in die Elemente wurde unter Knudsen-Bedingungen auf einer mit einem Massenspektrometer gekoppelten Thermowaage untersucht. Die Standardentropie, -enthalpie und die Debye-Temperaturen wurden berechnet. Die aus den Knudseneffusionsdaten abgeleiteten Dampfdruckfunktionen dienten zur Berechnung der Bildungswärmen. Die komplizierte Temperaturabhängigkeit der spezifischen Wärme wird für strukturelle Details und unterschiedliche Beiträge qualitativ diskutiert: fürT⩽K ein elektronischer Anteil, in der Ge-Verbindung im Bereich 2 K⩽T⩽20 K eine dreifache Schottky-Anomalie (ΔE0/k=46(2) K) sowie Gitterschwingungen, die durch unterschiedliche Abständed(Ag-Ag) und Massen (Ge und Sn) beeinflusst werden.
    Abstract: Резюме В интервале температ ур 2–310 К были измерены теплоемкости класте рных соединений [Ag6M4P12]Ge6, где M=Ge, Sn. Термическое разложение их на отде льные элементы было проведено в усло виях Кнудсена с помощ ью термовесов, соединен ных с массспектромет ром. Из данных теплоемкос тей были вычислены та кие термодинамические ф ункции, как стандартная энтр опия, энтальпия и темп ературы Дебая. Функции давлен ия паров, выведенные из эффузи онных данных Кнудсен а, служили для вычисления треть его закона теплообразования. Сл ожная температурная зависимость удельной теплоемкос ти количественно обсуждена с учетом ст руктурных деталей и р азличных вкладов: электронный член (Т⩽З К), трехосная аномалия Ш оттки (ΔEo/k=46(2) К) в соединен и германия (2 К⩽T⩽20 К), решеточные вклады, за трагиваемые расстоя ниями Ag-Ag и атомными массами (Ое и Sn) в обоих соединениях.
    Notes: Abstract The heat capacities of thecluster compounds [Ag6M4P12]Ge6 (M=Ge, Sn) have been measured in the temperature range from 2 K to 310 K. Thermal decomposition into the elements was carried out under Knudsen conditions on a thermobalance combined with a mass spectrometer. The thermodynamic functions standard entropy, enthalpy, and the Debye temperatures were calculated from the heat capacity data. The vapour pressure functions derived from the Knudsen effusion data, served to calculate the third law heat of formation. The rather complicated temperature dependence of the specific heat is qualitatively discussed by considering structural details and different contributions: electronic term (T≲/3 K), a threefold Schottky anomaly (ΔE 0/k=46(2) K)in the Ge-compounds (2 K⩽T⩽20 K), lattice contributions influenced by the distances Ag-Ag and atomic masses (Ge and Sn) in both compounds.
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  • 8
    ISSN: 1572-8943
    Keywords: calibration material ; calibration procedure ; DSC ; heat calibration ; heat flow rate calibration ; standards ; temperature calibration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Metrologically based measuring procedures and evaluation methods are recommended as guidance for practical temperature, heat and heat flow rate calibration of DSC instruments which are largely independent of instrumental, test and sample parameters. The relevant terms are defined, the measuring procedures and evaluation methods described, calibration materials and their characteristic data stated and guidance for the sample handling provided. Reference is made to three extended papers on calibration. The recommendations were developed by the working group ‘Calibration of Scanning Calorimeters’ of the German Society of Thermal Analysis (GEFTA).
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  • 9
    ISSN: 1572-8943
    Keywords: cupric oxide ; magnetic phase transitions ; specific heat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Anhand der spezifischen Wärme wurde in magnetischen Feldern bis zu 6T die antiferromagnetische Phasenumwandlung in einem CuO-Einkristall untersucht. Die Abhängigkeit der antiferromagnetischen Phasenumwandlung inkommensurabel/kommensurabel vom magnetischen Feld bei der TemperaturT L ist äußerst anisotrop.T L steigt fürB a ∥ c-Achse nichtlinear zu und nimmt fürB a ∥ b-Achse linear ab. Die Abhängigkeit vonT L vom magnetischen Feld und die Sprünge der magnetischen Suszeptibilität beiT L wurden unter Zuhilfenahme der Gleichung von Clausius-Clapeyron erklärt.
    Notes: Abstract The antiferromagnetic phase transitions in a CuO single crystal are studied by specific heat in magnetic fields up to 6T. The magnetic field dependence of the incommensurate-to-commensurate-antiferromagnetic transition atT L is found to be highly anisotropic.T L is observed to increase nonlinearly for Ba ∥c-axis, whereas, a linear reduction is observed forB a ∥b-axis. The magnetic field dependence ofT L and the jumps in magnetic susceptibility atT L are explained thermodynamically using the Clausius-Clapeyron equation.
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  • 10
    ISSN: 1572-8943
    Keywords: differential microcalorimeter ; heat capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird der Aufbau, die Funktions- und Arbeitsweise eines vollautomatisierten Differential-Mikrokalorimeters für Wärmekapazitätsmessungen kleiner Proben (m 〈 100 mg) im Temperaturbereich 15–300 K beschrieben. Die Funktionsweise des Gerätes beruht auf verschiedenen kalorimetrischen Methoden, insbesondere aufadiabatischem Differential-Scanning, Seine Zuverlässigkeit wird durch die Messung der Wärmekapazität einer 23 mg-Kupferprobe und einer 37 rag-Cyclopentanprobe mit einem Me\fehler von kleiner als 2% demonstriert.
    Notes: Abstract We describe the construction, operation and performance of a fully automated low temperature differential micro-calorimeter for heat capacity measurements on small samples (m 〈 100 mg) in the temperature range from 15 K to 300 K. The instrument is operated using different calorimetric methods, in particular adiabatic differential scanning. Its reliability is demonstrated by measuring the heat capacity of 23 mg of copper and 37 mg of cyclopentane with an error of less than 2%.
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