14 results on '"Hanna Schmid"'
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2. Posttreatment Lyme Disease Syndrome—What It Might Be and What It Is Not
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Ulrich Heininger and Hanna Schmid
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Microbiology (medical) ,myalgia ,medicine.medical_specialty ,Overdiagnosis ,medicine.drug_class ,Antibiotics ,Disease ,03 medical and health sciences ,0302 clinical medicine ,Lyme disease ,030225 pediatrics ,Humans ,Medicine ,030212 general & internal medicine ,Intensive care medicine ,Lyme Disease ,Post-Lyme Disease Syndrome ,Overtreatment ,business.industry ,Borrelia Burgdorferi Infection ,medicine.disease ,Diagnosis of exclusion ,Infectious Diseases ,Pediatrics, Perinatology and Child Health ,Symptom Assessment ,medicine.symptom ,Differential diagnosis ,business - Abstract
Lyme disease is a multisystem disease caused by Borrelia burgdorferi infection and accounts for well-defined manifestations, appearing either at an early or late stage. Appropriate antibiotic therapy generally leads to a favorable outcome. Still, unspecific persisting symptoms such as fatigue, myalgia, arthralgia or cognitive dysfunction are reported by several patients months to years after adequate treatment. Their underlying pathophysiologic mechanism is unclear. However, there is no evidence for microbiological persistence in these cases and attempts to resolve the symptoms by repeated or prolonged antibiotic treatment have not been convincingly successful, but they may rather be harmful. To narrow down the controversially handled entity of posttreatment Lyme disease syndrome (PTLDS) and to avoid overdiagnosis and overtreatment, case definitions have been proposed, acknowledging PTLDS as a complex of nonspecific, subjective symptoms, which are neither caused by ongoing infection nor by any other identifiable disease. PTLDS is mainly a diagnosis of exclusion and requires careful evaluation of differential diagnosis followed by counseling about optimal management in light of missing specific therapeutic options.
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- 2021
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3. Neonates with SARS-CoV-2 infection: spectrum of disease from a prospective nationwide observational cohort study
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Petra Zimmermann, Anita Uka, Michael Buettcher, Yves Fougère, Margherita Plebani, Christa Relly, Hanna Schmid, and Nicole Ritz
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Male ,Intensive Care Units ,Fever ,SARS-CoV-2 ,Infant, Newborn ,COVID-19 ,Humans ,Infant ,Female ,General Medicine ,Prospective Studies ,Child - Abstract
BACKGROUND: Coronavirus disease 2019 (COVID-19) can be more severe in infants than in older children. To date, only a few case series have reported data on neonates with COVID-19, including mostly asymptomatic neonates who were tested because of exposure to maternal SARS-CoV-2 infection. This study summarises nationwide epidemiological data, clinical characteristics, treatment and outcomes of neonates presenting with symptomatic SARS-CoV-2 infection. METHODS: Data were prospectively collected through the Swiss Paediatric Surveillance Unit from hospitalised neonates with laboratory-confirmed SARS-CoV-2 infection (positive polymerase chain reaction on a respiratory sample) from 1 March 2020 to 31 September 2021. All 29 paediatric hospitals in Switzerland reported cases. RESULTS: In total, 73 neonates were included; 7 (10%) were preterm. The median age at presentation was 17 days (interquartile range [IQR] 11–23); 40 (55%) were female. The majority of neonates (64, 88%) were admitted from home. Nine (12%) had a pre-existing medical condition. Overall, the most common symptom recorded was fever in 52 (71%), followed by rhinorrhoea or nasal congestion in 32 (44%) and respiratory distress in 19 (26%). Twenty (27%) neonates presented with fever without a source. Seven (10%) neonates were admitted to an intensive care unit (5 for respiratory failure and 2 for monitoring). One (1%) neonate required inotropic support. The median length of hospital stay in term neonates was 4 days (IQR 3–5). Two (3%) were treated with corticosteroids and 1 (1%) with remdesivir. In total, 60 (82%) neonates had contact with a known or suspected SARS-CoV-2 index case. All of the 71 neonates for whom data were available were discharged to their homes without symptoms. CONCLUSION: In neonates, COVID-19 mainly presents with fever, and symptoms of upper and lower respiratory tract infection. The clinical course is mostly mild, requiring a short period of hospitalisation. COVID-19 needs to be added as a differential diagnosis in neonates who present with fever without a source. However, the presence of SARS-CoV-2 should not deter from the search for a serious bacterial infection. Further data from surveillance studies are needed to better understand COVID-19 in neonates, guide therapy and to evaluate whether the clinical spectrum is changing with new SARS-CoV-2 variants.
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- 2022
4. Description of Pseudoclavibacter triregionum sp. nov. from human blood and Pseudoclavibacter albus comb. nov., and revised classification of the genus Pseudoclavibacter: proposal of Caespitibacter gen. nov., with Caespitibacter soli comb. nov. and Caespitibacter caeni comb. nov
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Peter Vandamme, Charlotte Peeters, Helena M. B. Seth-Smith, Hanna Schmid, Margo Cnockaert, Adrian Egli, and Daniel Goldenberger
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DNA, Bacterial ,RNA, Ribosomal, 16S ,Fatty Acids ,Humans ,General Medicine ,Sequence Analysis, DNA ,Molecular Biology ,Microbiology ,Phylogeny ,Bacterial Typing Techniques - Abstract
We present polyphasic taxonomic data to demonstrate that strain 125703-2019
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- 2022
5. COVID-19 in children and adolescents in Europe: a multinational, multicentre cohort study
- Author
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Benoît Bernar, Astrid Rojahn, Laura Jones, Elisabeth Schölvinck, Robin Kobbe, Laura Lancella, Delane Shingadia, Fiona Shackley, Lynne McFetridge, Conor Doherty, Cornelius Rau, Nicolaus Schwerk, Oksana Kozdoba, Koen Vanden Driessche, Arnaud G L'Huillier, Jasmin Pfefferle, Srini Bandi, R Song, Andreia Ribeiro, Ivan Solovic, Jonathan P. Glenthoej, Ulrich Heininger, Susana Melendo, Tine Boiy, Uros Krivec, An Bael, Luca Pierantoni, Edda Haberlandt, Miguel Lanaspa, Noémie Wagner, Andrea Lo Vecchio, Francesc Ripoll, Lise Heilmann Jensen, Piero Valentini, Anita Niederer, Roland Berger, Nicole Ritz, Aida M. Gutiérrez-Sánchez, Christelle Christiaens, Franziska Zucol, Katy Fidler, Jolanta Bernatoniene, Anna Starshinova, Volker Strenger, Claus Klingenberg, Ilona Lind, Clare S. Murray, Angela Zacharasiewicz, Ivan Pavic, Amanda Williams, Christina Thir, Vera Chechenyeva, Karsten Kötz, Stephanie Thee, Laura Buchtala, Danilo Buonsenso, Patrick Gavin, Rimvydas Ivaškevicius, Sara Debulpaep, Francesca Ippolita Calò Carducci, Marine Creuven, Beatriz Soto, Srđan Roglić, Lola Falcón, Yvonne Beuvink, Petra Zimmermann, Petra Schelstraete, Lynne Speirs, Daniela S. Kohlfürst, Antoni Noguera-Julian, Mihhail Tistsenko, Steven B. Welch, Hanna Schmid, Anastasios Smyrnaios, Laura Minguell, Andrew Riordan, Michael Buettcher, Angelika Berger, Isabel Carvalho, Daan Van Brusselen, Inga Ivaškeviciene, Matilde Bustillo, Valentina Vilc, Folke Brinkmann, Nina Krajcar, Olaf Neth, Alicia Demirjian, Matthias Bogyi, Ulle Uustalu, Maria Tsolia, Borja Ibanez, Elisabeth Whittaker, Ariane Biebl, Irini Eleftheriou, Burkhard Simma, Petra Prunk, Borbàla Zsigmond, Veronika Osterman, Zoe Oliver, Antoni Soriano-Arandes, Ulrikka Nygaard, Marcello Lanari, Marc Tebruegge, Olga Bilogortseva, Michael Barker, Svetlana Velizarova, Florian Götzinger, Natalia Gabrovska, Begoña Santiago-García, Benhur Şirvan Çetin, Paddy McMaster, Anna Zschocke, Frances Child, Nick Makwana, Mar Santos, Group, ptbnet COVID-19 Study, Gotzinger F., Santiago-Garcia B., Noguera-Julian A., Lanaspa M., Lancella L., Calo Carducci F.I., Gabrovska N., Velizarova S., Prunk P., Osterman V., Krivec U., Lo Vecchio A., Shingadia D., Soriano-Arandes A., Melendo S., Lanari M., Pierantoni L., Wagner N., L'Huillier A.G., Heininger U., Ritz N., Bandi S., Krajcar N., Roglic S., Santos M., Christiaens C., Creuven M., Buonsenso D., Welch S.B., Bogyi M., Brinkmann F., Tebruegge M., Pfefferle J., Zacharasiewicz A., Berger A., Berger R., Strenger V., Kohlfurst D.S., Zschocke A., Bernar B., Simma B., Haberlandt E., Thir C., Biebl A., Vanden Driessche K., Boiy T., Van Brusselen D., Bael A., Debulpaep S., Schelstraete P., Pavic I., Nygaard U., Glenthoej J.P., Heilmann Jensen L., Lind I., Tistsenko M., Uustalu U., Buchtala L., Thee S., Kobbe R., Rau C., Schwerk N., Barker M., Tsolia M., Eleftheriou I., Gavin P., Kozdoba O., Zsigmond B., Valentini P., Ivaskeviciene I., Ivaskevicius R., Vilc V., Scholvinck E., Rojahn A., Smyrnaios A., Klingenberg C., Carvalho I., Ribeiro A., Starshinova A., Solovic I., Falcon L., Neth O., Minguell L., Bustillo M., Gutierrez-Sanchez A.M., Guarch Ibanez B., Ripoll F., Soto B., Kotz K., Zimmermann P., Schmid H., Zucol F., Niederer A., Buettcher M., Cetin B.S., Bilogortseva O., Chechenyeva V., Demirjian A., Shackley F., McFetridge L., Speirs L., Doherty C., Jones L., McMaster P., Murray C., Child F., Beuvink Y., Makwana N., Whittaker E., Williams A., Fidler K., Bernatoniene J., Song R., Oliver Z., Riordan A., Gotzinger, F., Santiago-Garcia, B., Noguera-Julian, A., Lanaspa, M., Lancella, L., Calo Carducci, F. I., Gabrovska, N., Velizarova, S., Prunk, P., Osterman, V., Krivec, U., Lo Vecchio, A., Shingadia, D., Soriano-Arandes, A., Melendo, S., Lanari, M., Pierantoni, L., Wagner, N., L'Huillier, A. G., Heininger, U., Ritz, N., Bandi, S., Krajcar, N., Roglic, S., Santos, M., Christiaens, C., Creuven, M., Buonsenso, D., Welch, S. B., Bogyi, M., Brinkmann, F., Tebruegge, M., Pfefferle, J., Zacharasiewicz, A., Berger, A., Berger, R., Strenger, V., Kohlfurst, D. S., Zschocke, A., Bernar, B., Simma, B., Haberlandt, E., Thir, C., Biebl, A., Vanden Driessche, K., Boiy, T., Van Brusselen, D., Bael, A., Debulpaep, S., Schelstraete, P., Pavic, I., Nygaard, U., Glenthoej, J. P., Heilmann Jensen, L., Lind, I., Tistsenko, M., Uustalu, U., Buchtala, L., Thee, S., Kobbe, R., Rau, C., Schwerk, N., Barker, M., Tsolia, M., Eleftheriou, I., Gavin, P., Kozdoba, O., Zsigmond, B., Valentini, P., Ivaskeviciene, I., Ivaskevicius, R., Vilc, V., Scholvinck, E., Rojahn, A., Smyrnaios, A., Klingenberg, C., Carvalho, I., Ribeiro, A., Starshinova, A., Solovic, I., Falcon, L., Neth, O., Minguell, L., Bustillo, M., Gutierrez-Sanchez, A. M., Guarch Ibanez, B., Ripoll, F., Soto, B., Kotz, K., Zimmermann, P., Schmid, H., Zucol, F., Niederer, A., Buettcher, M., Cetin, B. S., Bilogortseva, O., Chechenyeva, V., Demirjian, A., Shackley, F., Mcfetridge, L., Speirs, L., Doherty, C., Jones, L., Mcmaster, P., Murray, C., Child, F., Beuvink, Y., Makwana, N., Whittaker, E., Williams, A., Fidler, K., Bernatoniene, J., Song, R., Oliver, Z., and Riordan, A.
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Male ,Delivery of Health Care / organization & administration ,medicine.medical_treatment ,Coronavirus Infections / therapy ,Coronavirus Infections / epidemiology ,law.invention ,Patient Admission ,0302 clinical medicine ,law ,Risk Factors ,COVID-19 ,children ,Europe ,Developmental and Educational Psychology ,030212 general & internal medicine ,Child ,ddc:618 ,Intensive care unit ,Coronavirus ,SARS-CoV-2 ,child ,treatment ,intensive care ,Intensive Care Units ,N/A ,Child, Preschool ,Female ,Europe / epidemiology ,Coronavirus Infections ,Human ,Cohort study ,medicine.medical_specialty ,Pneumonia, Viral / epidemiology ,Intensive Care Unit ,Pneumonia, Viral ,Patient Admission / trends ,Intensive Care Units / organization & administration ,Article ,Follow-Up Studie ,03 medical and health sciences ,Betacoronavirus ,030225 pediatrics ,Internal medicine ,Lower respiratory tract infection ,medicine ,Extracorporeal membrane oxygenation ,Humans ,Pediatrics, Perinatology, and Child Health ,Pandemics ,Pneumonia, Viral / therapy ,Mechanical ventilation ,Betacoronaviru ,Coronavirus Infection ,business.industry ,Risk Factor ,Infant, Newborn ,Infant ,Odds ratio ,medicine.disease ,ptbnet COVID-19 Study Group ,Clinical research ,El Niño ,Pediatrics, Perinatology and Child Health ,business ,Delivery of Health Care ,Follow-Up Studies - Abstract
Background To date, few data on paediatric COVID-19 have been published, and most reports originate from China. This study aimed to capture key data on children and adolescents with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection across Europe to inform physicians and health-care service planning during the ongoing pandemic. Methods This multicentre cohort study involved 82 participating health-care institutions across 25 European countries, using a well established research network—the Paediatric Tuberculosis Network European Trials Group (ptbnet)—that mainly comprises paediatric infectious diseases specialists and paediatric pulmonologists. We included all individuals aged 18 years or younger with confirmed SARS-CoV-2 infection, detected at any anatomical site by RT-PCR, between April 1 and April 24, 2020, during the initial peak of the European COVID-19 pandemic. We explored factors associated with need for intensive care unit (ICU) admission and initiation of drug treatment for COVID-19 using univariable analysis, and applied multivariable logistic regression with backwards stepwise analysis to further explore those factors significantly associated with ICU admission. Findings 582 individuals with PCR-confirmed SARS-CoV-2 infection were included, with a median age of 5·0 years (IQR 0·5–12·0) and a sex ratio of 1·15 males per female. 145 (25%) had pre-existing medical conditions. 363 (62%) individuals were admitted to hospital. 48 (8%) individuals required ICU admission, 25 (4%) mechanical ventilation (median duration 7 days, IQR 2–11, range 1–34), 19 (3%) inotropic support, and one ( Interpretation COVID-19 is generally a mild disease in children, including infants. However, a small proportion develop severe disease requiring ICU admission and prolonged ventilation, although fatal outcome is overall rare. The data also reflect the current uncertainties regarding specific treatment options, highlighting that additional data on antiviral and immunomodulatory drugs are urgently needed. Funding ptbnet is supported by Deutsche Gesellschaft für Internationale Zusammenarbeit.
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- 2020
6. MIS-C-Implications for the Pediatric Surgeon: An Algorithm for Differential Diagnostic Considerations
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Stephanie J. Gros, Isabella N. Bielicki, Stefan Holland-Cunz, Julia Bielicki, Matthias S. Matter, Claudia Höfele-Behrendt, Nora Manz, and Hanna Schmid
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medicine.medical_specialty ,Abdominal pain ,Physical examination ,Pediatrics ,differential diagnosis of appendicitis ,RJ1-570 ,Article ,acute abdomen ,Pediatric surgery ,pediatric surgery ,Medicine ,Medical history ,pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 ,Laparoscopy ,multisystem inflammatory syndrome in children ,medicine.diagnostic_test ,SARS-CoV-2 ,business.industry ,Pediatric Surgeon ,Acute abdomen ,Pediatrics, Perinatology and Child Health ,medicine.symptom ,Differential diagnosis ,business ,PIMS-TS ,Algorithm - Abstract
Background: multisystem inflammatory syndrome in children (MIS-C) is a new disease associated with a recent infection with severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). Affected children can present predominantly with abdominal symptoms, fever and high inflammatory parameters that might lead to a consult by the pediatric surgeon and an indication for surgery. Methods: clinical data of three patients with MIS-C that underwent surgery were collected. Histopathological analysis of the appendix was performed. Results: we present the clinical course of three children with fever, abdominal pain and vomiting for several days. Clinical examination and highly elevated inflammation markers led to indication for laparoscopy, appendectomy was performed in two patients. Because of intraoperative findings or due to lack of postoperative improvement, all patients were reevaluated and tested positive for MIS-C associated laboratory parameters and were subsequently treated with corticosteroids, intravenous immunoglobulins, acetyl salicylic acid and/or light molecular weight heparin. Conclusions: we discuss the implications of MIS-C as a new differential diagnosis and stress the importance of assessing the previous medical history, identifying patterns of symptoms and critically surveilling the clinical course. We implemented an algorithm for pediatric surgeons to consider MIS-C as a differential diagnosis for acute abdomen that can be integrated into the surgical workflow.
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- 2021
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7. Strain sensitive Pt–SiO2 nano-cermet thin films for high temperature pressure and force sensors
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Günter Schultes, S. Uhlig, Ulf Werner, and Hanna Schmid-Engel
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Materials science ,Annealing (metallurgy) ,Metals and Alloys ,Nanotechnology ,Cermet ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,Carbon film ,Transmission electron microscopy ,Electrical resistivity and conductivity ,Nano ,Electrical and Electronic Engineering ,Thin film ,Composite material ,Instrumentation - Abstract
The strain sensitivity, i.e. the resistivity change due to mechanical strain of thin composite nano-cermet films of Pt–SiO2 was investigated. We prepared films with a thickness of 400 nm by means of co-sputtering processes at substrate temperatures around 400 °C. The specimens respond to uniform strain (ɛ = 0.2‰) with gauge factors up to 18. These gauge factors remained high at least up to 250 °C in air and also after further annealing up to 600 °C in vacuum. Therefore we state these functional films might be suitable for high temperature pressure and force sensors. The films have a relatively high film resistivity of some MΩ/sq and exhibit temperature coefficients of resistance (TCR) in the range of −2000 ppm/K up to −600 ppm/K. X-ray diffraction revealed a single crystalline fcc platinum phase while transmission electron microscopy proved a typical granular structure of the films. Pt-clusters sized 5–10 nm are embedded in an amorphous insulating matrix of silica. The composition of such nano-cermet films displaying high gauge factors is approx. 40 at% Pt, 20 at% Si and 40 at% of O.
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- 2014
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8. Pressure sensitivity of piezoresistive nickel–carbon Ni:a-C:H thin films
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Günter Schultes, Tobias Speicher, Hanna Schmid-Engel, and Steffen Uhlig
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Materials science ,Hydrostatic pressure ,Metals and Alloys ,Analytical chemistry ,Condensed Matter Physics ,Piezoresistive effect ,Pressure sensor ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Sputtering ,Gauge factor ,Electrical and Electronic Engineering ,Thin film ,Instrumentation ,Temperature coefficient ,Bar (unit) - Abstract
The piezoresistive effects of nickel–carbon thin films, i.e., the sensitivity to hydrostatic pressure and uniform strain, are investigated in this study. Thin films, which were obtained by reactive sputtering processes with thicknesses up to 1200 nm, exhibit pressure sensitivity coefficients ( PCR ) about −20 ppm/bar and gauge factors up to 30 on Si/SiO 2 substrates. A linear change of the thin film's resistance in respect to the applied hydrostatic pressure was observed. Additionally, the temperature coefficients of resistance were determined in the range of −300 to 0 ppm/K, while the temperature coefficient of the PCR s was obtained as good as 0 ppm/K.
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- 2013
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9. Piezoresistive Ni:a-C:H thin films containing hcp-Ni or Ni3C investigated by XRD, EXAFS, and wavelet analysis
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Olivia Freitag-Weber, Roman Chernikov, Steffen Uhlig, Jochen Bock, Günter Schultes, Rudolf Paul Wilhelm Jozef Struis, Anne-Catherine Probst, Hanna Schmid-Engel, and Ivo Zizak
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Materials science ,Extended X-ray absorption fine structure ,Mechanical Engineering ,chemistry.chemical_element ,General Chemistry ,Piezoresistive effect ,Electronic, Optical and Magnetic Materials ,Crystal ,Crystallography ,chemistry ,Sputtering ,Phase (matter) ,ddc:550 ,Materials Chemistry ,Crystallite ,Electrical and Electronic Engineering ,Thin film ,Carbon - Abstract
Ni:a-C:H thin films obtained by reactive sputtering processes were investigated using EXAFS and subsequent wavelet analysis. Depending on overall thin film deposition conditions, the clusters of Ni in Ni:a-C:H can appear as fcc-Ni or as a non-fcc-Ni phase, such as hcp-Ni or Ni3C. While hcp-Ni and Ni3C are hardly distinguishable by XRD, the EXAFS analysis can reveal if carbon is the nearest neighbour of Ni or not, thus if Ni3C is present or hcp-Ni. Our study showed that wavelet transformation analysis of the EXAFS data is necessary to discriminate clearly between hcp-Ni and Ni3C regarding the presence or absence of carbon coordination shells around the X-ray absorbing Ni atoms. Furthermore, we are confident to have identified Ni3C in our thin films, however, we cannot exclude the possibility of the co-existence of hcp-Ni. Finally, calculations of XRD peaks of hcp-Ni and Ni3C showed that a discrimination of these two crystal phases might be feasible when the crystallite size is increased beyond 40 nm.
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- 2013
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10. Structural and physical properties of highly piezoresistive nickel containing hydrogenated carbon thin films
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Ulf Werner, Ralf Koppert, Anne-Catherine Probst, Dirk Göttel, Hanna Schmid-Engel, Günter Schultes, and S. Uhlig
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Materials science ,Mechanical Engineering ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Piezoresistive effect ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,Nickel ,Carbon film ,chemistry ,Chemical engineering ,Sputtering ,Gauge factor ,Materials Chemistry ,Electrical and Electronic Engineering ,Nichrome ,Thin film - Abstract
Nickel containing amorphous hydrogenated carbon (Ni:a-C:H) thin films prepared by reactive sputtering have a high potential for use as piezoresistive sensors. Investigations by means of X-ray diffraction (XRD), transmission electron microscopy, energy-dispersive X-ray spectroscopy, and magnetic characterizations indicate that sputtering parameters and heat treatment influence the film composition, the microscopic structure, and some relevant macroscopic physical properties. The films are heterogeneous in nature and consist of either nanometer sized hcp nickel, nickel carbide (these phases being indistinguishable by XRD), or fcc nickel clusters encapsulated by graphite-like carbon shells. The nature of the metal clusters in the thin films has a strong effect on its magnetic properties. For approximately 55 at.% Ni the electrical resistivity of the film is nearly temperature independent over a broad temperature range from 100 K to 400 K. The strain sensitivity, with a gauge factor of 20, is up to ten times higher than conventional temperature independent strain sensitive films. Compared to industry standard NiCr functional layers used for pressure sensors, Ni:a-C:H films provide a ten fold higher output signal.
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- 2012
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11. C3 - Piezoresistive nano-Cermet-Funktionsschichten für Hochtemperaturanwendungen
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Günter Schultes, Hanna Schmid-Engel, and S. Uhlig
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Materials science ,Nano ,Cermet ,Composite material ,Piezoresistive effect - Published
- 2013
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12. P6.3 - Novel Carbon-Based Materials for Pressure and Force Sensors
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Ralf Koppert, Dirk Göttel, Hanna Schmid-Engel, Günter Schultes, and Ulf Werner
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Materials science ,chemistry ,chemistry.chemical_element ,Composite material ,Carbon ,Force sensor - Published
- 2011
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13. Trap-controlled hole transport in small molecule organic semiconductors
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Heinz von Seggern, Arne Fleissner, Christian Melzer, and Hanna Schmid
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Organic semiconductor ,Electron mobility ,Physics and Astronomy (miscellaneous) ,Chemistry ,Doping ,Density of states ,Relaxation (physics) ,Charge carrier ,Atomic physics ,Ionization energy ,Amorphous solid - Abstract
The influence of trap concentration on hole transport is investigated by an optical time-of-flight method for the amorphous small molecule organic semiconductor N,N′-bis(1-naphtyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamin (α-NPD) doped with neutral hole traps by codeposition of 4,4′,4″-tris-[N-(1-naphtyl)-N-(phenylamino)]-triphenylamine (1-NaphDATA). α-NPD doped with 120ppm 1-NaphDATA exhibits nondispersive hole transport like undoped α-NPD, but trap-controlled with reduced mobility. The trap depth derived from the mobility decrease coincides with the ionization potential difference of α-NPD and 1-NaphDATA. The transition to dispersive transport for increasing trap concentration to 1160ppm is explained by an energetic relaxation of optically generated charge carriers within a density of states broadened by traps.
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- 2007
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14. Transition from non-dispersive to dispersive hole transport in a small molecule organic semiconductor controlled by molecular doping
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Hanna Schmid, Roland Schmechel, Heinz von Seggern, Christian Melzer, and Arne Fleissner
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Organic semiconductor ,Range (particle radiation) ,Electron mobility ,Materials science ,Dopant ,Electric field ,Doping ,Organic chemistry ,Charge carrier ,Thin film ,Molecular physics - Abstract
The influence of charge carrier traps on charge carrier transport is studied in a small molecule organic semiconductor model system by means of an optical time-of-flight method. The model system consists of the hole transport material N,N'-di(1-naphtyl)-N,N'-diphenylbenzidine (α-NPD, sometimes denoted as α-NPB) either undoped or doped with various concentrations of the small molecule 4,4',4”-tris-[N-(1-naphtyl)-N-(phenylamino)]-triphenylamine (1-NaphDATA), which is known to create hole traps in α-NPD.In case of undoped α-NPD, non-dispersive hole transport is observed and the hole mobility is determined as 6·10−4cm2/Vs in the examined electric field range, being in good agreement with published data. Depending on the intensity of the laser light employed for optical charge carrier generation, current transients both in the space-charge regime and in the small signal case are obtained. In the small signal case the current transients do not exhibit the expected flat current plateau before the characteristic kink that marks the transit time, but feature a cusp instead. A tentative mechanism for its formation is proposed.The influence of the trap concentration on charge carrier transport is studied by introducing 1-NaphDATA as a molecular dopant. It is demonstrated that the hole transport in α-NPD can be controlled by varying the doping concentration of 1-NaphDATA. Increasing the trap concentration, a transition from non-dispersive transport in undoped α-NPD to non-dispersive but trap-controlled transport with reduced mobility and further to dispersive transport is observed.
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