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Ahrenberg M, Shoifet E, Whitaker KR, Huth H, Ediger MD, Schick C. Differential alternating current chip calorimeter for in situ investigation of vapor-deposited thin films. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:033902. [PMID: 22462933 DOI: 10.1063/1.3692742] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Physical vapor deposition can be used to produce thin films with interesting material properties including extraordinarily stable organic glasses. We describe an ac chip calorimeter for in situ heat capacity measurements of as-deposited nanometer thin films of organic glass formers. The calorimetric system is based on a differential ac chip calorimeter which is placed in the vacuum chamber for physical vapor deposition. The sample is directly deposited onto one calorimetric chip sensor while the other sensor is protected against deposition. The device and the temperature calibration procedure are described. The latter makes use of the phase transitions of cyclopentane and the frequency dependence of the dynamic glass transition of toluene and ethylbenzene. Sample thickness determination is based on a finite element modeling of the sensor sample arrangement. In the modeling, a layer of toluene was added to the sample sensor and its thickness was varied in an iterative way until the model fit the experimental data.
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El-Taweel SH, Stoll B, Schick C. Crystallization kinetics and miscibility of blends of polyhydroxybutyrate (PHB) with ethylene vinyl acetate copolymers (EVA). E-POLYMERS 2011. [DOI: 10.1515/epoly.2011.11.1.191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractA series of ethylene vinyl acetate random copolymer EVA, with vinyl acetate (VA) varied from 9 to 91m%, was investigated by differential scanning calorimetry DSC and polarized optical microscopy. Biodegradable polymer blends of polyhydroxybutyrate PHB and EVA, having VA in EVA in range from 40m% till 91m%, were prepared by film casting from a chloroform solution. The miscibility and crystallization behavior of these blends were investigated. The isothermal crystallization behaviors of PHB and PHB/EVA blends are discussed in terms of the half time of crystallization t1/2. Experimental results indicated that blends of PHB/ EVA91 are completely miscible blend in the entire (0 to 100 m%) compositional ranges. Blends PHB/ EVA, for VA varied from 40 till 70 m% are immiscible as evidenced by the existence of unchanged composition independent glass transition temperatures (Tg), crystallization and melting behavior. The isothermal crystallization of PHB blends was investigated from room temperature till 130 °C. 80 °C was found to be the best temperature for comparison of different blends. At 80 °C t1/2 strongly depends on the content of VA in PHB/EVA blend, mainly due to differences in miscibility as well as due to differences in segmental mobility as identified by differences in glass transition temperature. Since both components in PHB/EVA80, pure PHB and pure EVA80, have glass transition temperatures close to 0 °C, it is difficult to decide its miscibility from Tg. However from the strong dependence of the value of crystallization half time t1/2 of PHB/EVA80 on blend composition, it was possible to reasonably infer that PHB/EVA80 is partially miscible.
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Emel’yanenko VN, Verevkin SP, Schick C, Stepurko EN, Roganov GN, Georgieva MK. The thermodynamic properties of S-lactic acid. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2010. [DOI: 10.1134/s0036024410090074] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Yang B, Gao Y, Zou C, Zhai Q, Zhuravlev E, Schick C. Size-dependent undercooling of pure Sn by single particle DSC measurements. CHINESE SCIENCE BULLETIN-CHINESE 2010. [DOI: 10.1007/s11434-010-3041-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Weber T, Cammerer G, Schick C, Solbach C, Hillenbrand A, Barth TF, Henne-Bruns D, Blagieva R, Böhm BO, Reske SN, Luster M. C-11 methionine positron emission tomography/computed tomography localizes parathyroid adenomas in primary hyperparathyroidism. Horm Metab Res 2010; 42:209-14. [PMID: 20013649 DOI: 10.1055/s-0029-1243185] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
In patients with primary hyperparathyroidism (pHPT), positive preoperative localization studies enable to perform a minimally invasive approach for parathyroid surgery. However, current imaging techniques are not always successful. We therefore conducted a study to determine the sensitivity of C-11 methionine positron emission tomography/computed tomography (Met-PET/CT) in localizing parathyroid adenomas in pHPT. Met-PET/CT scans of the neck and mediastinum of 33 patients undergoing parathyroidectomy for primary HPT were compared with intraoperative and histological findings. Primary HPT was caused by a single gland adenoma in 30 patients, while another 3 patients had multiglandular disease. Met-PET/CT scan correctly located a single gland adenoma in 25 out of 30 (83%) patients with pHPT, among them 2 patients with persistent disease, 7 patients with prior neck surgery, and 8 patients with concomitant thyroid nodules. In 3 patients with multiglandular disease, Met-PET/CT showed only one enlarged parathyroid gland in two individuals and was negative in the third patient. Statistical analysis found a significant correlation between true-positive results and the weight (2.42+/-4.05 g) and diameter (2.0+/-1.18 cm) of parathyroid adenomas while the subgroup with false negative findings had significantly smaller (0.98+/-0.54 cm) and lighter (0.5+/-0.38 g) glands. Sensitivity was 83% for single gland adenomas and 67% for multiglandular disease. Met-PET/CT correctly localized 83% of single gland parathyroid adenomas in patients with pHPT. However, preoperative localization of multiglandular disease due to double adenomas or parathyroid hyperplasia remained difficult.
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Wurm A, Minakov A, Schick C. Simultaneous Calorimetric, Dielectric, and SAXS/WAXS Experiments During Polymer Crystallization. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/978-3-540-95968-7_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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Serghei A, Huth H, Schick C, Kremer F. Glassy Dynamics in Thin Polymer Layers Having a Free Upper Interface. Macromolecules 2008. [DOI: 10.1021/ma702381t] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Minakov AA, Wurm A, Schick C. Superheating in linear polymers studied by ultrafast nanocalorimetry. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2007; 23:43-53. [PMID: 17510749 DOI: 10.1140/epje/i2007-10173-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Accepted: 04/25/2007] [Indexed: 05/15/2023]
Abstract
To study phase transition kinetics on submillisecond time scale a sensitive ultrafast nanocalorimeter was constructed. Controlled ultrafast cooling, as well as heating, up to 10(6) K/s was attained. The method was applied for the measurements of the superheating phenomenon in a set of linear polymers: iPS, PBT, PET, and iPP. A power law relation between the superheating and the heating rate holds in the heating rate range 10(-2) - 10(4) K/s. A limiting superheating of about 10% of the melting temperature was observed at rates above 10(4) - 10(5) K/s. This limit depends on annealing conditions before sample melting. The observed superheating limit, as well as the power law, can be accounted for the internal stresses near the crystalline amorphous interface in semicrystalline polymers induced by heating, which are related to the thermal expansion gradients inherent in a semicrystalline material.
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Merzlyakov M, Wurm A, Zorzut M, Schick C. Frequency and temperature amplitude dependence of complex heat capacity in the melting region of polymers. J MACROMOL SCI B 2006. [DOI: 10.1080/00222349908248158] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Wurm A, Merzlyakov M, Schick C. Crystallization of polymers studied by temperature-modulated techniques (TMDSC, TMDMA). J MACROMOL SCI B 2006. [DOI: 10.1080/00222349908248132] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Tol R, Minakov A, Adamovsky S, Mathot V, Schick C. Metastability of polymer crystallites formed at low temperature studied by ultra fast calorimetry: Polyamide 6 confined in sub-micrometer droplets vs. bulk PA6. POLYMER 2006. [DOI: 10.1016/j.polymer.2006.01.052] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Huth H, Minakov AA, Schick C. Differential AC-chip calorimeter for glass transition measurements in ultrathin films. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/polb.20921] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Pyda M, Nowak-Pyda E, Heeg J, Huth H, Minakov AA, Di Lorenzo ML, Schick C, Wunderlich B. Melting and crystallization of poly(butylene terephthalate) by temperature-modulated and superfast calorimetry. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/polb.20789] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Jansen MAG, Goossens JGP, de Wit G, Bailly C, Schick C, Koning CE. Poly(butylene terephthalate) Copolymers Obtained via Solid-State Polymerization and Melt Polymerization. A Study on the Microstructure via 13C NMR Sequence Distribution. Macromolecules 2005. [DOI: 10.1021/ma051440j] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Serghei A, Mikhailova Y, Huth H, Schick C, Eichhorn KJ, Voit B, Kremer F. Molecular dynamics of hyperbranched polyesters in the confinement of thin films. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2005; 17:199-202. [PMID: 15912265 DOI: 10.1140/epje/i2005-10009-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Accepted: 04/05/2005] [Indexed: 05/02/2023]
Abstract
Broadband Dielectric Spectroscopy is employed to investigate the molecular dynamics in thin films of hyperbranched polyesters (type AB(1)B(2), with -OH and -OCOCH(3) as terminal groups). Three relaxation processes are detected: alpha, beta and gamma. While the latter two are not influenced by the confinement, a pronounced effect is observed on the alpha relaxation: with decreasing film thickness the slower relaxation modes of the dynamic glass transition are gradually suppressed, resulting in an increase of the average relaxation rate and in a linear decrease of the dielectric strength. This is attributed to an immobilization in confinement of the polymeric segments located at the periphery of the hyperbranched macromolecular structures.
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Serghei A, Huth H, Schellenberger M, Schick C, Kremer F. Pattern formation in thin polystyrene films induced by an enhanced mobility in ambient air. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 71:061801. [PMID: 16089755 DOI: 10.1103/physreve.71.061801] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Revised: 02/11/2005] [Indexed: 05/03/2023]
Abstract
Thin polystyrene films (prepared in a sandwich geometry between two aluminum electrodes) develop a characteristic pattern in ambient air when kept above the glass-transition temperature, whereas they remain unchanged in vacuum or in a pure nitrogen atmosphere. Measurements by broadband dielectric spectroscopy, capacitive dilatometry, and AC calorimetry reveal that the pattern formation is initiated in ambient air by an increase in the average relaxation rate of the dynamic glass transition, which results in a corresponding reduction of the glass-transition temperature. Infrared measurements evidence that this is caused by a shift of the molecular weight distribution to lower values as a consequence of oxygen-induced chain scissions.
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Sch�nhals A, Goering H, Schick C, Frick B, Zorn R. Glass transition of polymers confined to nanoporous glasses. Colloid Polym Sci 2004. [DOI: 10.1007/s00396-004-1106-3] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Rastogi R, Vellinga WP, Rastogi S, Schick C, Meijer HEH. The three-phase structure and mechanical properties of poly(ethylene terephthalate). ACTA ACUST UNITED AC 2004. [DOI: 10.1002/polb.20096] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Vogl T, Schick C, Mack M, Gstöttner W. Bildgebende Diagnostik und Differentialdiagnostik von pathologischen Prozessen des Sinus cavernosus. ROFO-FORTSCHR RONTG 2004. [DOI: 10.1055/s-2004-827447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Vogl TJ, Schick C, Mack M, Gstöttner W. [Diagnostic imaging and differential diagnosis of pathological processes of the sinus cavernosus]. Radiologe 2003; 43:161-70. [PMID: 12624673 DOI: 10.1007/s00117-003-0861-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
To describe the different imaging modalities for the evaluation of pathological changes in the cavernous sinus as well as to compile criteria for differential diagnosis. Imaging of the cavernous sinus comprises the primary use of tomographic modalities such as CT or MRI. The continuing development of multislice-CT (MSCT) allows the depiction of bony structures of the cavernous sinus with a high resolution.Secondary reconstructions of the acquired data set allow a reliable evaluation especially of the bony topography including the foraminae of nerves and vessels. Uni- or bilateral structures can be visualized using contrast-enhanced CT.CT-angiography is capable of demonstrating the course of the internal carotid artery and its involvement in pathologies of the cavernous sinus, this recent achievement has only been made available by use of the current short scanning times. Contrast-enhanced MRI in axial and coronal orientation, optionally using fat saturation techniques as well as arterial and venous MRI-angiography (MRA) are used to depict the soft parts of the cavernous sinus. Care must be taken to cover all topographic detail including different signal intensities, as multiple inborn, neoplastic, infectious or traumatic changes can be present hampering the radiologic diagnosis of the cavernous sinus. Uni- and bilateral infiltration of the cavernous sinus as well as vascular involvement represent additional criteria leading to the differential diagnosis. The advent of dynamic sequences as well as diffusion and perfusion weighted MRI have broadened the spectrum of diagnostic modalities. Digital subtraction angiography as an invasive technique is used during therapeutic procedures such as the local treatment of aneurysms or carotid-cavernous fistulas.
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Rödel F, Hoffmann J, Haas J, Grabenbauer G, Schick C, Günther K, Sauer R, Rödel C. Expression of survivin in rectal cancer is inversely correlated to apoptosis in-vitro and in-vivo and may predict tumor response to neoadjuvant radiochemotherapy. Int J Radiat Oncol Biol Phys 2002. [DOI: 10.1016/s0360-3016(02)03229-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Jacobi V, Thalhammer A, Schick C, Peters J, Vogl T. Notched ureter sign. Eur Radiol 2002; 12:2120-2. [PMID: 12211179 DOI: 10.1007/s00330-002-1348-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Abolmaali N, Langenfeld M, Krahforst R, Schick C, Thalhammer A, Schmitt J, Schulze T, Schächinger V, Vogl TJ. Vessel wall MRI of the thoracic aorta: correlation to histology and transesophageal ultrasound. Preliminary results. ROFO-FORTSCHR RONTG 2002; 174:568-72. [PMID: 11997855 DOI: 10.1055/s-2002-28272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE To visualise the vessel wall of the descending thoracic aorta using magnetic resonance imaging. To evaluate the diagnostic potential of tailored T1-weighted sequences with contrast enhancement to assess systemic atherosclerotic disease. METHODS This study was performed on a clinical 1.5 Tesla scanner using a gradient strength of 30 mT/m and the phased array spine coil. A cadaver was examined to optimise a magnetic resonance imaging (MRI) protocol to evaluate atherosclerotic aortic wall disease. The acquired MR images were compared to gross specimens and histology. Subsequently seven patients who had undergone transesophageal ultrasound (TEU) with detailed assessment of the descending thoracic aorta were examined with MRI. The optimised protocol included untriggered and fat suppressed T2-weighted turbo spin echo sequences and ECG-triggered and fat suppressed T1-weighted spin echo sequences before and after iv administration of Gd-DTPA. Findings of the MR images were compared to the results of TEU. Contrast enhancement measurements were performed in normal and thickened vessel wall segments. RESULTS For the cadaver study a good correlation of the degree of vessel wall thickening and the extent of plaque imaged with the applied MR protocol was found. Tissue characterisation was limited due to post mortem changes. In vivo ECG-triggered T1-weighted images showed good correlation to TEU in terms of vessel wall thickness and plaque extension as verified by means of consensus reading. Differentiation of the plaque components fat, calcium and fibrous tissue was possible. In thickened aortic wall segments and fibrous caps a mean contrast enhancement of 50.4 % +/- 23.5 % was measurable while normal wall segments showed an enhancement of 6.7 % +/- 3.1 %. The difference of contrast enhancement was highly significant (p < 0.0001). CONCLUSION Using fat suppressed T1-weighted sequences with contrast enhancement the extent of atherosclerotic vessel wall changes can be demonstrated. The suggested MR protocol contains a high potential for diagnosis and follow-up of therapy of atherosclerotic disease of the descending thoracic aorta.
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Schick C. Temperature modulated differential scanning calorimetry (TMDSC) – basics and applications to polymers. APPLICATIONS TO POLYMERS AND PLASTICS 2002. [DOI: 10.1016/s1573-4374(02)80019-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Schick C, Sukhorukov D, Schönhals A. Comparison of the Molecular Dynamics of a Liquid Crystalline Side Group Polymer Revealed from Temperature Modulated DSC and Dielectric Experiments in the Glass Transition Region. MACROMOL CHEM PHYS 2001. [DOI: 10.1002/1521-3935(20010501)202:8<1398::aid-macp1398>3.0.co;2-c] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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