TY - GEN A1 - Hansen, Felix A1 - Wels, Martin A1 - Froeschke, Samuel A1 - Popov, Alexey A1 - Wolf, Daniel A1 - Büchner, Bernd A1 - Schmidt, Peer A1 - Hampel, Silke T1 - Thermodynamic Evaluation and Chemical Vapor Transport of Few-Layer WTe2 T2 - Crystal Growth and Design N2 - Tungsten telluride WTe2 is the sole candidate of a group of two-dimensional layered transition metal dichalcogenides (TMDCs) MX2 with a thermodynamically stable 1T′-structure at room temperature. The binary system W/Te was audited with respect to a rational approach of planning and realization of a bottom-up synthesis of WTe2 nanostructures. Thus, the parameters of the synthesis via chemical vapor transports (CVT) were derived by thermodynamic simulations of the reaction pathway according to the Calphad method. Reflecting on the peritectic melting behavior at 1020 °C, the values of ΔfHm° (298 K) = −26.5 kJ·mol−1 and Sm° (298 K) = 132 J·mol−1 ·K−1 have been obtained. According to modeling, crystal growth by short time vapor transport is reasonable under the addition of bromine or TeBr4 in the temperature range between 650 and 750 °C. Experimental implementation of crystal growth of WTe2 nanosheets succeeded in a temperature gradient from 725 to 675 °C on yttria-stabilized zirconia (YSZ) (111) substrates, observing the deposition of single crystal sheets of high crystallinity with thicknesses of 15−20 nm (∼20−30 layers). The high crystallinity, pristine morphology, and overall quality of the deposited nanosheets is shown by means of atomic resolution transmission electron microscopy, selected area electron diffraction (SAED), and atomic force microscopy as well as profound double-polarized Raman spectroscopy. KW - Crystal growth KW - Chemical vapor transport KW - Thermodynamic modeling KW - 2D layered compounds KW - Chalcogenides KW - Phase diagram Y1 - 2020 UR - https://pubs.acs.org/doi/abs/10.1021/acs.cgd.0c01004 U6 - https://doi.org/10.1021/acs.cgd.0c01004 SN - 1528-7505 VL - 20 IS - 11 SP - 7341 EP - 7349 ER - TY - RPRT A1 - Böttger, Stefan A1 - Felgentreff, Bernd A1 - Hesse, Gerold A1 - Hloucal, Martin-Joseph A1 - Leßmann, Dieter A1 - Mix, Sebastian A1 - Roselt, Kersten A1 - Safarik, Mathias A1 - Schmidt, Jörg A1 - Steffan, Christoph A1 - Uhlmann, Wilfried T1 - Seethermie - Innovative Wärmeversorgung aus Tagebaurestseen - Schlussbericht KW - Seethermie Y1 - 2021 UR - https://www.innovationsregion-mitteldeutschland.com/wp-content/uploads/2021/07/20210723_Schlussbericht-Seethermie_Langfassung.pdf CY - Leipzig ER - TY - GEN A1 - Froeschke, Samuel A1 - Bestha, Kranthi Kumar A1 - Fucke, Rico A1 - Schiemenz, Sandra A1 - Popov, Alexey A1 - Naumann, Marco A1 - Knupfer, Martin A1 - Giebeler, Lars A1 - Wolf, Daniel A1 - Kizhake Malayil, Ranjith Kumar A1 - Sivan, Saramgi Chencheriparambil A1 - Grafe, Hans-Joachim A1 - Gräßler, Nico A1 - Corredor, Laura T. A1 - Wolter, Anja U. B. A1 - Büchner, Bernd A1 - Schmidt, Peer A1 - Hampel, Silke T1 - Structural and Magnetic Transitions Caused by Dimer Formation in the CrCl3–MoCl3 Solid Solution T2 - Chemistry of Materials N2 - In this work, we apply the concept of solid solutions to the two 2D transition metal trihalides CrCl3 and MoCl3. While CrCl3 belongs to the magnetically active CrX3 family, the magnetism in MoCl3 is intrinsically suppressed by the formation of aligned Mo–Mo dimers, which also distort the regular honeycomb lattice that is typical for the 2D transition metal trihalides. We report suitable synthesis conditions for the gapless solid solution and crystal growth by chemical vapor transport. The CrCl3–MoCl3 solid solution was initially synthesized at 650 °C for 100 h under addition of MoCl5 as mineralizer, and bulk crystals were subsequently grown by vapor transport in a temperature gradient from 600 °C → 550 °C for 60 h. The obtained solid solution exhibits multiple composition-dependent phase transitions at room temperature, as confirmed by powder X-ray diffraction measurements. The possible presence of Mo–Mo dimers in the solid solution was further investigated by infrared, Raman, electron energy loss, and nuclear quadrupole resonance spectroscopies. The combined results indicate that the Mo–Mo dimers are present over a wide range of compositions. Their orientation changes from parallel alignment for compositions from 70% ≤ c(Mo3+) ≤ 100% to random orientation for samples with c(Mo3+) < 70% content, which significantly affects the course of lattice parameters. Finally, the magnetic properties of the powder samples show a correlation between the Mo3+ content and the transition temperature into the low-temperature phase. Y1 - 2024 U6 - https://doi.org/10.1021/acs.chemmater.3c03109 SN - 0897-4756 SN - 1520-5002 VL - 36 IS - 9 SP - 4240 EP - 4253 ER - TY - GEN A1 - Froeschke, Samuel A1 - Yasmen, Nadia A1 - Popov, Alexey A1 - Schiemenz, Sandra A1 - Wolf, Daniel A1 - Giebeler, Lars A1 - Hantusch, Martin A1 - Gräßler, Nico A1 - Büchner, Bernd A1 - Schmidt, Peer A1 - Hampel, Silke T1 - Controlled Nanoplatelet Deposition of 2D Chromium Trihalide Solid Solutions T2 - Chemistry of Materials N2 - The two-dimensional (2D) chromium trihalides CrCl3, CrBr3, and CrI3 are most famous for their exotic magnetic properties when their crystals get downscaled to nanometer dimensions. One way to tune the properties of such materials and to further increase their potential utility, e.g., in spintronics, is the formation of solid solutions. Here, we present a detailed theoretical and experimental study on the synthesis and nanoplatelet growth of CrBrxCl3–x and CrBrxI3–x solid solutions. Phase pure powder was obtained by tempering the respective parent compounds at 600 and 550 °C, using additional iodine in the case of CrBrxI3–x. The dominant stacking order changes at x = 1.8 for CrBrxCl3–x while remaining similar to CrI3 for the whole CrBrxI3–x series. A consecutive chemical vapor transport from 575 → 525 °C for 2 h (CrBrxCl3–x) or 600 → 550 °C for 3 h with 0.1 mmol additional iodine (CrBrxI3–x) resulted in the deposition of high-quality nanoplatelets on a substrate with only several nanometers in height. The composition can be controlled by the choice of the starting material, since only small shifts in the anion ratio occur during the transport. The deposited CrBrxCl3–x nanoplatelets can then be easily delaminated by ultrasonication in ethanol to reduce the height even further to few-layer dimensions. These nanoplatelets could potentially be used to investigate the property changes (e.g., in terms of magnetic response) for the downscaling of these solid solutions. We further demonstrate the quality of the deposited material by transmission electron microscopy, selected area electron diffraction, and X-ray photoelectron spectroscopy. Raman spectroscopy of the solid solution series reveals a complex evolution of vibrational modes. Photoluminescence measurements on solid solution samples show emission peaks in the near-infrared energy range with the specific energy and intensity being composition and temperature dependent. KW - 2D layered compounds KW - Chemical vapor transport KW - Crystal growth KW - Crystal structure KW - Halides KW - Thermodynamic modeling Y1 - 2023 UR - https://pubs.acs.org/doi/full/10.1021/acs.chemmater.2c03785 U6 - https://doi.org/10.1021/acs.chemmater.2c03785 SN - 1520-5002 SN - 0897-4756 VL - 35 IS - 11 SP - 4136 EP - 4148 ER - TY - GEN A1 - Lützner, Jörg A1 - Deckert, Stefanie A1 - Lange, Toni A1 - Postler, Anne Elisabeth A1 - Aringer, Martin A1 - Berth, Hendrik A1 - Bork, Hartmut A1 - Dreinhöfer, Karsten E A1 - Günther, Klaus-Peter A1 - Heller, Karl-Dieter A1 - Hube, Robert A1 - Kirschner, Stephan A1 - Kladny, Bernd A1 - Kopkow, Christian A1 - Sabatowski, Rainer A1 - Stoeve, Johannes A1 - Wagner, Richard A1 - Lützner, Cornelia T1 - Evidenzbasierte und patientenorientierte Indikationsstellung zur Knieendoprothese – Update der Leitlinie T2 - Zeitschrift für Orthopädie und Unfallchirurgie N2 - ZusammenfassungDie Implantation einer Knieendoprothese zählt mit ca. 170000 Eingriffen pro Jahr zu den am häufigsten stationär durchgeführten Operationen in Deutschland. Eine einheitliche, angemessene und patientenorientierte ärztliche Indikationsstellung ist bei einem solchen Eingriff unerlässlich. Das Update der S2k-Leitlinie „Indikation Knieendoprothese“ beinhaltet auf aktueller Evidenz basierende und im breiten Konsens abgestimmte Empfehlungen und eine Checkliste im praxistauglichen Format.Für dieses Leitlinien-Update wurde eine systematische Literaturrecherche nach (inter-)nationalen Leitlinien und systematischen Übersichtsarbeiten zur Gonarthrose und Knieendoprothetik durchgeführt, um klinisch relevante Fragestellungen zu Diagnostik, Prädiktoren für das Outcome, Risikofaktoren und Kontraindikatoren zu beantworten.Eine Knieendoprothese soll nur bei radiologisch nachgewiesener fortgeschrittener Gonarthrose (Kellgren-Lawrence-Grad 3 oder 4), nach vorangegangener konservativer Therapie über mindestens 3 Monate sowie bei hohem subjektivem Leidensdruck hinsichtlich der kniebezogenen Beschwerden und nach Ausschluss möglicher Kontraindikationen (Infektionen, Begleiterkrankungen, BMI ≥ 40 kg/m2) erfolgen. Modifizierbare Risikofaktoren (wie Rauchen, Diabetes mellitus, Anämie) sollen zuvor adressiert und ggf. optimiert werden. Die Ziele der Patient*innen sollen erfragt und deren Eintrittswahrscheinlichkeit gemeinsam besprochen werden. Schließlich ist die Entscheidung zur Knieendoprothese von Patient*in und Operateur*in gemeinsam zu treffen, wenn der zu erwartende Nutzen die möglichen Risiken überwiegt.Das Update der S2k-Leitlinie wurde um die unikondyläre Knieendoprothese erweitert, die präoperative Optimierung modifizierbarer Risikofaktoren ergänzt sowie Konkretisierungen der Hauptindikationskriterien vorgenommen. Y1 - 2024 U6 - https://doi.org/10.1055/a-2288-7254 SN - 1864-6697 PB - Georg Thieme Verlag KG ER - TY - GEN A1 - Beirow, Bernd A1 - Nakos, Alex A1 - Stecklina, Caroline A1 - Noack, Martin A1 - Firl, Matthias A1 - Sasakaros, Marios T1 - Implementation of intentional mistuning by means of finite element based shape optimization T2 - Journal of engineering for gas turbines and power N2 - Intentional Mistuning has turned out to be an effective measure to alleviate the maximum forced response of bladed wheels in the framework of numerous studies in the past. In particular solutions based on two different blade designs, following e.g. alternating or AABB patterns, have proved to be promising in this regard and moreover robust against the impact of unavoidable random mistuning. Thus, for example, a 40 percent reduction of the first blade bending maximum forced response has been proved experimentally for a turbine impeller of a turbo charger application. Despite this success, the technical implementation of the frequency based mistuning pattern followed an academic solution based on locally removing material at the leading edge tip, which is not suited for the use in serial wheels since it may disturb the flow channel. In addition, the forced response of other blade modes may be affected in a negative manner. In order to overcome these problems, an alternative way of implementing Intentional Mistuning is suggested by applying a marginal geometric modification of the blade thickness distribution to adjust the natural frequency of the first bending mode. Finite element based shape optimization is utilized to this end. Secondary conditions are ensuring that only the target frequency of the first bending mode is adjusted whereas natural frequencies of other modes are kept almost unchanged. Y1 - 2025 U6 - https://doi.org/10.1115/1.4069624 SN - 0742-4795 SP - 1 EP - 15 PB - ASME International CY - New York ER - TY - GEN A1 - Beirow, Bernd A1 - Nakos, Alex A1 - Stecklina, Caroline A1 - Noack, Martin A1 - Firl, Matthias A1 - Sasakaros, Marios T1 - Implementation of intentional mistuning by means of finite element based shape optimization BT - Volume 9 : structures and dynamics : structural mechanics & vibration; supercritical CO2 T2 - Proceedings of the ASME Turbo Expo 2025, Memphis, June 16–20, 2025 N2 - Intentional Mistuning has turned out to be an effective measure to alleviate the maximum forced response of bladed wheels in the framework of numerous studies in the past. In particular solutions based on two different blade designs, following e.g. alternating or AABB patterns, have proved to be promising in this regard and moreover robust against the impact of unavoidable random mistuning. Thus, for example, a 40 percent reduction of the first blade bending maximum forced response has been proved experimentally for a turbine impeller of a turbo charger application. Despite this success, the technical implementation of the frequency based mistuning pattern followed an academic solution based on locally removing material at the leading edge tip, which is not suited for the use in serial wheels since it may disturb the flow channel. In addition, the forced response of other blade modes may be affected in a negative manner. In order to overcome these problems, an alternative way of implementing Intentional Mistuning is suggested by applying a marginal geometric modification of the blade thickness distribution to adjust the natural frequency of the first bending mode. Finite element based shape optimization is utilized to this end. Secondary conditions are ensuring that only the target frequency of the first bending mode is adjusted whereas natural frequencies of other modes are kept almost unchanged. KW - Intentional Mistuning KW - Turbine Impeller KW - Forced Response KW - Shape Optimization Y1 - 2025 SN - 978-0-7918-8885-8 U6 - https://doi.org/10.1115/GT2025-151617 PB - The American Society of Mechanical Engineers CY - New York, NY ER - TY - GEN A1 - Lee, Roh Pin A1 - Huang, Qiuliang A1 - Yuchi, Wei A1 - Zhang, Tingting A1 - Bai, Jin A1 - Gräbner, Martin A1 - Meyer, Bernd T1 - Public knowledge, perception & support for alternative transformation routes towards sustainable waste management : a case analysis of Taiyuan in Shanxi Province, China T2 - 13th International Freiberg Conference on Circular Carbon Technologies KW - Sustainable waste management Y1 - 2025 SN - 2363-8702 ER - TY - GEN A1 - Schmitt, Ingo A1 - Sowoidnich, Kay A1 - Gosswami, Tapashi A1 - Sumpf, Bernd A1 - Maiwald, Martin A1 - Wolff, Matthias T1 - PCA-based peak feature selection for classification of spectroscopic datasets T2 - Journal of chemometrics N2 - Reducing feature dimensionality in spectroscopic data is crucial for efficient analysis and classification. Using all available features for classification typically results in an unacceptably high runtime and poor accuracy. Popular feature extraction methods, such as principal component analysis (PCA), linear discriminant analysis (LDA), and autoencoders, reduce feature dimensionality by extracting latent features that can be challenging to interpret. To enable better human interpretation of the classification model, we avoid extraction methods and instead propose applying feature selection methods. In this work, we develop an innovative PCA-based feature selection method for spectroscopic data, providing an essential subset of the original features. As an important advantage, no prior knowledge about the characteristic signals of the respective target substance is required. In this proof-of-concept study, the proposed method is initially characterized using simulated Raman and infrared absorption datasets. From the top five PCA eigenvectors of spectroscopic data, we identify a set of three top peaks each at specific wavenumbers (features). The compact set of selected features is then used for classification tasks applying a decision tree. Based on two well-defined spectroscopic datasets, our study demonstrates that our new method of PCA-based peak finding outperforms selected other approaches with regard to interpretability and accuracy. For both investigated datasets, accuracies greater than 97% are achieved. Our approach shows large potential for accurate classification combined with interpretability in further scenarios involving spectroscopic datasets. KW - Cclassification KW - Decision tree KW - Peak finding KW - Principal component analysis KW - Spectroscopic data Y1 - 2025 U6 - https://doi.org/10.1002/cem.70074 SN - 0886-9383 SN - 1099-128X VL - 39 IS - 11 SP - 1 EP - 14 PB - John Wiley & Sons Ltd. CY - New York, NY ER -