428 results match your criteria: "Clausthal University of Technology[Affiliation]"

Various polycations and polyanions were sequentially adsorbed onto the gold electrode of a quartz crystal microbalance with dissipation monitoring. The study focused on determining the adsorption kinetics, viscoelastic properties, and electroresponsivity of polyelectrolyte layers. For the first time, it was demonstrated that the structure (compact or expanded) of the layers can be determined by electroresponsivity.

View Article and Find Full Text PDF

In response to climate change mitigation efforts, improving the efficiency of heat networks is becoming increasingly important. An efficient operation of energy systems depends on faultless performance. Following the need for effective fault detection and elimination methods, this study suggests a three-step workflow for increasing automation in managing defective substations on the user level within heat networks.

View Article and Find Full Text PDF

Polyurethane (PUR) soft foams release malodorous and potentially toxic compounds when exposed to oxidative conditions. Current chamber test methods cannot distinguish between pre-existing volatiles and those formed during oxidation, nor can they assess the formation rates of oxidation products. We subjected PUR soft foam to oxidative treatment in a continuous air flow at 120 °C.

View Article and Find Full Text PDF

Itaconates available from renewable resources constitute a group of monomers that are used in several types of polymerizations. Their use in free-radical polymerizations (FRPs) is still limited due to the low propagation rate coefficients resulting in low polymerization rates and the occurrence of depropagation which is responsible for limited monomer conversion. Since FRP is considered very robust with few requirements concerning monomer purity, it is still interesting to investigate how itaconate FRP may become feasible.

View Article and Find Full Text PDF

Recent advances in laser scanning systems have enabled the acquisition of 3D point cloud representations of scenes, revolutionizing the fields of Architecture, Engineering, and Construction (AEC). This paper presents a novel pipeline for the automatic generation of 3D semantic models of multi-level buildings from indoor point clouds. The architectural components are extracted hierarchically.

View Article and Find Full Text PDF

State-of-the-art object detection models need large and diverse datasets for training. As these are hard to acquire for many practical applications, training images from simulation environments gain more and more attention. A problem arises as deep learning models trained on simulation images usually have problems generalizing to real-world images shown by a sharp performance drop.

View Article and Find Full Text PDF

High-temperature polymerizations involving self-initiation of the monomer are attractive because of high reaction rate, comparable lower viscosities, and no need for an additional initiator. However, the polymers obtained show a more complex microstructure, e.g.

View Article and Find Full Text PDF

Mesoionic compounds are the starting material for the synthesis of unique anionic N-heterocyclic carbenes. Herein, mesoionic imidazolium pyrrolides synthesized from pyrrole-2-carbaldehyde via various -alkyl-4-pyrroyl-imidazoles are described. These were converted into nine new 4-(pyrrol-2-yl)-substituted imidazolium salts and transformed into the mesoionic title compounds using an anion exchange resin.

View Article and Find Full Text PDF

Self-Diffusion of Ge in Amorphous Ge Si Films Studied In Situ by Neutron Reflectometry.

ACS Mater Au

September 2024

Institute of Metallurgy, Solid State Kinetics Group, Clausthal University of Technology, Clausthal-Zellerfeld 38678, Germany.

Ge Si alloys are gaining renewed interest for many applications in electronics and optics, especially for miniaturized devices showing quantum size effects. Point defects and atomic diffusion play a crucial role in miniaturized and metastable systems. In the present work, Ge self-diffusion in sputter deposited amorphous Ge Si alloys is studied in situ as a function of Ge content = 0.

View Article and Find Full Text PDF

This study aims to fine-tune the plasma composition with a particular emphasis on reactive nitrogen species (RNS) including nitrogen dioxide (NO), dinitrogen pentoxide (NO), and nitrous oxide (NO), produced by a self-constructed cylindrical dielectric barrier discharge (CDBD). We demonstrated the effective manipulation of the plasma chemical profile by optimizing electrical properties, including the applied voltage and frequency, and by adjusting the nitrogen and oxygen ratios in the gas mixture. Additionally, quantification of these active species was achieved using Fourier transform infrared spectroscopy.

View Article and Find Full Text PDF

Lentiviral vector and virus-like particle (VLP) manufacturing have been published in fed-batch upstream and batch downstream modes before. Batch downstream and continuous upstream in perfusion mode were reported as well. This study exemplifies development and validation steps for a digital twin combining a physical-chemical-based mechanistic model for all unit operations with a process analytical technology strategy in order to show the efforts and benefits of autonomous operation approaches for manufacturing scale.

View Article and Find Full Text PDF

Lattice-Cluster-Theory-Informed Cross-Fractionation Chromatography Revealing Degree of Crystallinity of Single Macromolecular Species.

ACS Macro Lett

August 2024

Chair of Technical Thermodynamics and Energy Efficient Material Treatment, Institute for Energy Process Engineering and Fuel Technology, Clausthal University of Technology, Agricolastraße 4, 38678 Clausthal-Zellerfeld, Germany.

The relationship between macromolecular architecture and crystallization properties is a relevant research topic in polymer science and technology. The average degree of crystallinity of disperse polymers is a well-studied quantity and is accessible by various experimental methods. However, how the different macromolecular species contribute to the degree of crystallinity and, in particular, the relationship between a certain macromolecular architecture and the degree of crystallinity are not accessible today, neither experimentally nor theoretically.

View Article and Find Full Text PDF

Hydrodistillation and solid-liquid extraction with organic solvents or supercritical CO are standard technologies for natural product manufacturing. Within this technology, portfolio pressurized hot water technology is ranked as a green, sustainable, resilient, kosher and halal manufacturing process. Essential for sustainability is energy integration for heating and cooling the auxiliary water as well as product concentration without evaporation but with the aid of low energy consuming ultra- and nanofiltration membrane technology.

View Article and Find Full Text PDF

This study investigates the influence of heat treatments on the corrosion behaviour of CuSn10 tin bronze, additively manufactured using Laser Powder Bed Fusion (LPBF). LPBF enables the creation of finely structured, anisotropic microstructures, whose corrosion behaviour is not yet well understood. After production, specimens were heat-treated at 320 °C, 650 °C, and in a two-stage treatment at 800 °C and 400 °C, followed by hardness and microstructure analysis.

View Article and Find Full Text PDF

Spark ablation was used to continuously synthesize bimetallic L1 Pt/Fe nanoparticles in an aerosol process involving a furnace and hydrogen as a reducing process gas. For the formation of Pt/Fe in the favorable L1 crystal configuration, which is a promising electrocatalyst, the Pt-Fe ratio plays a crucial role. State-of-the-art analytics for such multi-element nanoparticles include, among others, electron microscopy (EM) with an element mapping function, such as scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy (STEM-EDXS).

View Article and Find Full Text PDF

Plasmid DNA is an important substance for the pharmaceutical industry. A major challenge in its production is the clarification of the lysate after harvesting. In this work, a novel process for this is demonstrated in an annular centrifugal contactor (ACC) with an aqueous two-phase extraction.

View Article and Find Full Text PDF

Quartz crystal microbalance with dissipation monitoring (QCM-D) has become a major tool enabling accurate investigation of the adsorption kinetics of nanometric objects such as DNA fragments, polypeptides, proteins, viruses, liposomes, polymer, and metal nanoparticles. However, in liquids, a quantitative analysis of the experimental results is often intricate because of the complex interplay of hydrodynamic and adhesion forces varying with the physicochemical properties of adsorbates and functionalized QCM-D sensors. In the present paper, we dissect the role of hydrodynamics for the analytically tractable case of stiff contact, whereas the adsorbed rigid particles oscillate with the resonator without rotation.

View Article and Find Full Text PDF

Engineered artificial minerals (EnAMs) are the core of a new concept of designing scavenger compounds for the recovery of critical elements from slags. It requires a fundamental understanding of solidification from complex oxide melts. Ion diffusivity and viscosity play vital roles in this process.

View Article and Find Full Text PDF

Control of Interface Migration in Nonequilibrium Crystallization of LiSiO from LiO-SiO Melt by Spatiotemporal Temperature and Concentration Fields.

ACS Omega

May 2024

Chair of Technical Thermodynamics and Energy Efficient Material Treatment, Institute of Energy Process Engineering and Fuel Technology, Clausthal University of Technology, Agricolastraße 4, 38678 Clausthal-Zellerfeld, Germany.

During liquid-solid transformation, bulk mass and thermal diffusion, along with the evolved interfacial latent heat, work in tandem to generate interfacial thermodynamic and kinetic forces, the interplay of which decides the solidification velocity and consequently the solidified phase attributes. Hence, access to interface dynamics information in dependence of bulk transfer processes is pivotal to tailor the desired quantity of solid phases of unique compositions. It finds particular application for engineering concentrated Lithium (Li) phases out of Li-ion battery slags, thus generating a high value-added product from a conventional waste process stream.

View Article and Find Full Text PDF

Influence of Water Hardness and Complexing Agents on Electrochemical Hydrogen Peroxide Generation.

ChemSusChem

October 2024

Institute of Chemical and Electrochemical Process Engineering, Clausthal University of Technology, Leibnizstraße 17, 38678, Clausthal-Zellerfeld, Germany.

Recently, many studies have been published regarding electrochemical oxygen reduction reaction for generating hydrogen peroxide (HO) using gas diffusion electrodes (GDEs) for various applications. Sodium salts solved in deionized water were usually used as supporting electrolytes. In technical applications, however, tap water-based electrolytes with hardeners are particularly relevant and have only been considered in a few studies to date.

View Article and Find Full Text PDF

Analytical Perspectives on Cement Sheath Integrity: A Comprehensive Review of Theoretical Research.

ACS Omega

April 2024

National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, P. R. China.

Article Synopsis
  • The cement sheath is essential for well barriers, providing zonal isolation, corrosion protection for casing, and mechanical support, crucial as the petroleum industry moves toward deep unconventional resources.
  • Increased complexities in the environment, such as high temperatures and pressures, raise the risk of cement sheath failure, driving a focus on analyzing stress distribution and failure modes in the casing-cement formation system.
  • The paper reviews theoretical research on cement sheath integrity, covering failure concepts, constitutive and analytical models, and numerical simulations, aiming to enhance understanding and inform future practices and research.
View Article and Find Full Text PDF

Influence of additives and binder on the physical properties of dental silicate glass-ceramic feedstock for additive manufacturing.

J Mech Behav Biomed Mater

July 2024

Division 5.4 Advanced Multi-materials Processing, Bundesanstalt für Materialforschung und -prüfung, Unter Den Eichen 87, 12205, Berlin, Germany.

Objectives: The aim of the study was to investigate the impact of organic additives (binder, plasticizer, and the cross-linking ink) in the formulation of water-based feedstocks on the properties of a dental feldspathic glass-ceramic material developed for the slurry-based additive manufacturing technology "LSD-print."

Material And Methods: Three water-based feldspathic feedstocks were produced to study the effects of polyvinyl alcohol (AC1) and poly (sodium 4-styrenesulfonate) (AC2) as binder systems. A feedstock without organic additives was tested as the control group (CG).

View Article and Find Full Text PDF
Article Synopsis
  • The study investigates the plastic properties of a high-entropy alloy (HfNbTaTiZr) using simulated nanoindentation tests, comparing it to a standard Ta crystal.
  • Key findings reveal that the high-entropy alloys exhibit less dislocation relaxation and minimal dislocation emission compared to the Ta crystal, indicating unique dislocation behavior.
  • The presence of short-range order in the alloy increases its stiffness and hardness, leads to a larger plastic zone and higher dislocation density, and eliminates twinning plasticity, contrasting with the behavior of the elemental Ta under stress.
View Article and Find Full Text PDF

Flotation of the mineral lithium aluminate by application of the natural product punicine from Punica granatum and some derivatives as collectors is examined. Punicines, 1-(2',5'-dihydroxyphenyl)-pyridinium compounds, are switchable molecules whose properties can be changed reversibly. They exist as cations, neutral mesomeric betaines, anions, and dianions depending on the pH.

View Article and Find Full Text PDF

Novel porous poly(methyl methacrylate) (PMMA) silica nanocomposites have been produced by utilization of polymerization-induced phase separation in a simple one-pot approach. A facile free radical polymerization of MMA in the presence of surface methacrylate-functionalized silica nanoparticles was carried out in ethanol-based solvents, successfully producing novel, morphologically designable porous nanocomposite monoliths. Differing from standard free radical polymerization in solution, a mixture of good and poor solvents (ethanol/,-dimethylformamide ratio) for the resulting polymer was used to trigger spinodal phase separation.

View Article and Find Full Text PDF