M. Proske, S. Boles-Herresthal, D. Latorre-Bastidas
et al.
Compact, customizable, non-magnetic vacuum systems are a key requirement for many field applications of quantum technology based on cold atoms. We report on the development and construction of a compact, low-cost ultra-high vacuum compatible cell using the glass-ceramic MACOR. The cell offers a CF flange connection to commercial vacuum technology, as well as high numerical aperture viewports for precision optical measurements. The presented technology shows stable vacuum pressures of $< 1 \cdot 10^{-10}$ mbar for more than a year since the implementation into the vacuum system of a quantum gas experiment, further proving suitability for general quantum technology applications.
Phyllosilicate clays have diverse applications in packaging industries and are found highly suitable for formulation, including thermoplastic starch (TPS), polyethylene (PE), or their combination. We developed CG MARTINI-3 parameters of the pyrophyllite using Lifshitz theory and experimental surface tension data. These initial bead assignments of pyrophyllite and periodic tetramethylammonium-montmorillonite (TMA-MMT) sheet were fine-tuned using optimal reproduction of structural, thermodynamic, and dynamic properties obtained via all-atom (AA) simulation of TPS with a periodic pyrophyllite sheet. These developed models predicted the correct AA radial distribution function and two-body excess entropy for polymer-sorbitol pairs, showcasing the robustness of the developed CG model in predicting the properties not used in parameterization. These composite simulations revealed acceleration (for pyrophyllite) or retardation (for TMA-MMT) of khun segment dynamics (compared to melt) with the depletion of polymer near the surface. The developed CG parameters were used to investigate the long-time behavior of TPS-polyethylene (PE) melt and their Cloisite-15A-based composite systems. The coordination number indicated compatibilization of the TPS-PE phase, achieved by binding TPS through its bare polar surface and PE via alkyl-mediated interactions, which consequently reduced the TPS-PE interfacial surface tension from 45 mN/m to 13.06 mN/m. Additionally, high TPS-clay coordination, sustained localization of clay at the TPS-PE interface, and clay aggregation observed in CG simulation closely agree with experimental observations. Further, the CG model effectively captured the clay-mediated variation in the overall morphology of the TPS-PE system and their direct impact on chain conformational properties, making this CG model highly suitable for a material design perspective.
Clay-rich soils and sediments are key components of near-surface systems, influencing water retention, ion exchange, and structural stability. Their complex dielectric behavior under moist conditions arises from electrostatic interactions between charged mineral surfaces and exchangeable cations, forming diffuse double layers that govern transport and retention processes. This study investigates the broadband dielectric relaxation of four water-saturated clay minerals (kaolin, illite, and two sodium-activated bentonites) in the 1 MHz to 5 GHz frequency range using coaxial probe measurements. The dielectric spectra were parameterized using two phenomenological models - the Generalized Dielectric Relaxation Model (GDR) and the Combined Permittivity and Conductivity Model (CPCM) - alongside two theoretical mixture models: the Augmented Broadband Complex Dielectric Mixture Model (ABC-M) and the Complex Refractive Index Model (CRIM). These approaches were evaluated for their ability to link dielectric relaxation behavior to petrophysical parameters such as cation exchange capacity (CEC), volumetric water content (VWC), and porosity. The results show distinct spectral signatures correlating with clay mineralogy, particularly in the low-frequency range. Relaxation parameters, including relaxation strength and apparent DC conductivity, exhibit strong relationships with CEC, emphasizing the influence of clay-specific surface properties. Expansive clays like bentonites showed enhanced relaxation due to ion exchange dynamics, while deviations in a soda-activated bentonite highlighted the impact of chemical treatments on dielectric behavior. This study provides a framework for linking clay mineral physics with electromagnetic methods, with implications for soil characterization, hydrological modeling, geotechnical assessment, and environmental monitoring.
Novel Co and Cr free, high-temperature (Ni, Mn) co-doping CuFe5O8 black ceramic pigments were synthesized. The effects of mineralizer type and mineralizer amount on the synthesis and coloration of (Ni, Mn) co-doping CuFe5O8 pigments, as well as the effect of glazing calcination temperature on glaze coloration were systematically investigated using testing and characterization methods such as XRD, FE-SEM, TEM, EDS-mapping, HAADF and colorimeter. The results indicate that compared with H3BO3, NH4F, LiF and NaF mineralizers, the pigment with MgO as the mineralizer is relatively better. The optimized mineralizer MgO amount is 6.25 wt.% (mass ratio relative to the pigment). L*, a* and b* values of corresponding optimized pigment are 21.36, 1.10 and -0.24, respectively. The crystal phase of the pigment is CuFe5O8 (73–2314), and no diffraction peak of the heterophase is detected. The crystal size of the pigments is 0.8–1.5 μm with excellent dispersivity. The glazing temperatures have little effect on the coloration of the pigments when they are used at 1000 °C, 1150 °C and 1300 °C. The results show that the pigment has excellent high temperature resistance and is expected to be widely used in high-temperature glazing coloration.
Simone Taraborelli, Simone Failla, Diletta Sciti
et al.
The impact of high-energy milling using WCCo media on the pressureless sintering and properties of TiB2 was studied. After 30 mins of milling, samples sintered at 2200 °C achieved a high relative density (>98 %) and a fine mean grain size (<2 µm). In the microstructure WxBy phases, often containing Co, were observed at triple points, due to contamination from the milling media. Moreover, core-rim structures with multiple rims were detected: the cores consisted of pure TiB2 grains, the rims were (TixWy)B2 solid solutions. The core-rim formation was significantly more pronounced compared to a reference sample of the same powder mixture densified by hot pressing at 1900 °C. The hardness reached 23 GPa, comparable to the hot-pressed sample, while the fracture toughness remained within 4.8–5.1 MPa·m1/2 up to 1000 °C. The strength was approximately 350–400 MPa up to 1000 °C, declining sharply at higher temperatures due to W-containing impurities. Thermal diffusivity and conductivity were similarly impacted by these impurities.
Maximilian Bundscherer, Thomas H. Schmitt, Tobias Bocklet
In industrial manufacturing of glass bottles, quality control of bottle prints is necessary as numerous factors can negatively affect the printing process. Even minor defects in the bottle prints must be detected despite reflections in the glass or manufacturing-related deviations. In cooperation with our medium-sized industrial partner, two ML-based approaches for quality control of these bottle prints were developed and evaluated, which can also be used in this challenging scenario. Our first approach utilized different filters to supress reflections (e.g. Sobel or Canny) and image quality metrics for image comparison (e.g. MSE or SSIM) as features for different supervised classification models (e.g. SVM or k-Neighbors), which resulted in an accuracy of 84%. The images were aligned based on the ORB algorithm, which allowed us to estimate the rotations of the prints, which may serve as an indicator for anomalies in the manufacturing process. In our second approach, we fine-tuned different pre-trained CNN models (e.g. ResNet or VGG) for binary classification, which resulted in an accuracy of 87%. Utilizing Grad-Cam on our fine-tuned ResNet-34, we were able to localize and visualize frequently defective bottle print regions. This method allowed us to provide insights that could be used to optimize the actual manufacturing process. This paper also describes our general approach and the challenges we encountered in practice with data collection during ongoing production, unsupervised preselection, and labeling.
Cr2AlC-20 wt% (Sn; Cu; Co; Fe; Ag) powder mixtures were hot isostatically pressed at 1000 °C for 4 h under 150 MPa to investigate the possible alloying behaviour of the metals with the MAX phase. The as-synthesized bulk materials were further oxidized at 1000 and 1200 °C for 10 h under dry air flux to study the effect of the alloying on the oxidation performance of the MAX phase. The metallic elements did not dissolve into the MAX phase grains: they mainly acted as oxidizing agents on the MAX phase grains, draining the aluminum from it to form intermetallic phases. The oxidation tests resulted in the formation of an alumina scale for most of the samples. The oxidation kinetic study shows no improvement of the oxidation behaviour of the Cr2AlC-metal composites as compared to pure bulk Cr2AlC. Sn spheres embedded in an alumina layer and empty alumina shells are respectively observed on the surface of the oxidized Cr2AlC–Sn and Cr2AlC–Ag composites.
Chiara Molinari, Andreea Sima, Matteo Cavina
et al.
Granite extraction waste represents an interesting alternative material for porcelain stoneware production, but information on its influence presents several gaps. For this reason, two different wastes were selected: a coarser iron-rich material from magnetic separation and a finer one from conveyance and abatement systems. Both were physically and chemically characterized. Batches were formulated by partial substitution of feldspar and technological behaviour of bodies was assessed by simulating the industrial manufacture at laboratory scale. Tiles were shaped by uniaxial pressure and fired by fast firing in electric roller kiln. The effect of waste addition was evaluated during the whole production process. Fired samples were characterized in terms of technological properties, mineralogical composition and microstructure evolution. The formulation optimization reduces firing temperature getting commercial technological constraints. A further increase of finer waste content affects compaction and mechanical strength. The presence of micaceous particles after the firing process may act as cracks initiation.
To improve the oxidation resistance of short carbon fiber (Csf)-reinforced mechanically alloyed SiBCN (MA-SiBCN) (Csf/MA-SiBCN) composites, dense amorphous Csf/SiBCN composites containing both MA-SiBCN and polymer-derived ceramics SiBCN (PDCs-SiBCN) were prepared by repeated polymer infiltration and pyrolysis (PIP) of layered Csf/MA-SiBCN composites at 1100 °C, and the oxidation behavior and damage mechanism of the as-prepared Csf/SiBCN at 1300–1600 °C were compared and discussed with those of Csf/MA-SiBCN. The Csf/MA-SiBCN composites resist oxidation attack up to 1400 °C but fail at 1500 °C due to the collapse of the porous framework, while the PIP-densified Csf/SiBCN composites are resistant to static air up to 1600 °C. During oxidation, oxygen diffuses through preexisting pores and the pores left by oxidation of carbon fibers and pyrolytic carbon (PyC) to the interior of the matrix. Owing to the oxidative coupling effect of the MA-SiBCN and PDCs-SiBCN matrices, a relatively continuous and dense oxide layer is formed on the sample surface, and the interfacial region between the oxide layer and the matrix of the as-prepared composite contains an amorphous glassy structure mainly consisting of Si and O and an incompletely oxidized but partially crystallized matrix, which is primarily responsible for improving the oxidation resistance.
In addition to static loads, structural glazing joints in glass and facade construction in many regions are subject to extraordinary effects such as earthquakes. Seismic actions are characterized by a randomly recurring and dynamic load that affects the structural behavior of the viscoelastic material. Publications on the load-bearing behavior and design of structural glazing joints against seismic loading have not systematically considered these effects. In this paper, relevant parameters influencing the seismic loading of structural glazing joints are determined, evaluated, and narrowed down to areas of practical relevance as part of a theoretical stress analysis.
On this basis, extensive experimental investigations of the low-cycle fatigue behavior of structural glazing joints are presented. Cyclic stress-strain curves are determined and compared with quasi-static reference tests to describe the basic low-cycle fatigue behavior. The influence of the previously determined parameters on the cyclic load-bearing behavior can thus be determined and presented. These investigations provide an important basis for describing the behavior under typical seismic random loading. In particular, the type of load application caused by the different construction types of glass and facade buildings can be mentioned as a decisive influencing factor in addition to the frequency of building construction. The results provide a first important contribution to the modeling and design of structural glazing joints against earthquake effects. Within the framework of the IGF project "RISIKO", further extensive scientific investigations will be carried out on this basis in order to develop a design model for structural glazing joints in disaster scenarios.
The rapid development of miniaturization and refinement of modern electronic components has led to higher requirements for nanosized powders. The barium strontium titanate (Ba1-xSrxTiO3, BST) nanopowders with fine grains, uniform particle size and high purity have broad application prospects. Herein, BST nanopowders were synthesized via nonhydrolytic sol-gel method and the effects of different processing parameters on structure were investigated systematically by using X-ray diffraction, transmission electron microscopy, laser particle size analyser and thermogravimetric mass spectrometry. In the first step, different dispersants, dispersant concentration and calcination temperature were selected for synthesis of Ba0.6Sr0.4TiO3 powder to find optimal conditions. In the second step, these optimal conditions were used to synthesize BST powders, but different (Ba+Sr)/Ti and Ba/Sr molar ratios were used to find those that can enable preparation of single phase cubic perovskite powder. Therefore, this study showed how the processing parameters can be systematically tuned with the idea to obtain ultra-fine single phase BST nanoparticles.
The utility of Nru clay for industrial application, which was taken from the Nsukka local government area in Enugu State, Nigeria, is assessed in this study for its physical and chemical properties. The clay was investigated chemically which showed SiO 2 51.2%, Al 2 O 3 18.3% as the predominant constituents while other metallic oxides such as Fe 2 O 3 5.3%, MgO 2.2%, Na 2 O 1.8%, CaO 1.4%, K 2 O 1.3% and MnO 0.7% were present in considerable proportion. The physical and mechanical analysis acknowledged a range in the linear shrinkage (4.17 - 6.25%), total shrinkage (7.8 - 10.2%), apparent porosity (36.92 – 26.58%), apparent density (2.59 - 2.37 g/cm3), bulk density (1.63 - 1.74 g/cm3), water absorption (22.64 – 15.33%) and modulus of rupture (6.70 – 9.15 kg/cm2) with an increase in firing temperature from 900°C to 1200°C. Nru clay can withstand heat without melting or deforming at temperature up to 1200 °C and exhibited reasonable plasticity with a modulus of plasticity of 1.42. We can infer from our investigation that Nru clay is a potential raw material for industries in the production of ceramics, high melting clays, fired bricks, and paints. Alternatively, the clays’ properties can be tailored to achieve superior physical and mechanical properties by enhancing them with additives. Therefore, it can be employed to cushion the exorbitant cost of importing clay minerals from other nations.
In this work, we have carried out molecular dynamics (MD) simulation techniques to study the diffusion coefficient of interlayer molecules at different temperature. Within the wider context of water dynamics in soils, and with a particular emphasis on clays, we present here the translational dynamics of water in clays, in a bi-hydrated states. We focus on temperatures between 293 K and 350 K, i.e., the range relevant to the environmental waste packages. A natural hectorite clay of interest is modified as a synthetic clay, which allows us to understand the determinantal parameters from MD simulations through a comparison with the experimental values. The activation energy E a determined by our simulation is [8.50 - 16.62] KJ/mol. The calculated diffusive constants are in the order of 10^{-5} {cm^{2}}/s. The simulation results are in good agreement with experiments for the relevant set of conditions, and they give more insight into the origin of the observed dynamics.
Potassium tantalate (KTaO$_{3}$) is a promising material for dielectric applications at low temperature. However, dense and single-phase ceramics cannot be obtained by conventional sintering because of the evaporation of potassium that leads to secondary phases. Here, we demonstrate that spark plasma sintering is a suitable method to obtain dense and single-phase KTaO$_{3}$ ceramics, by optimizing three parameters: initial composition, temperature, and pressure. A 2 mol% K-excess in the precursors leads to a large grain growth and dense single-phase ceramics. Without K-excess, a small amount of secondary phase (K$_{6}$Ta$_{10.8}$O$_{30}$) is observed at the surface but can be removed by polishing. At 10 K, the dielectric permittivity is 4 times higher in the ceramic from the 2 mol% K-excess powder, because of the larger grain size. The thermal conductivity decreases with decreasing grain size and stays above the thermal conductivity of KNbO$_{3}$ ceramics.
Jean-Philippe Bouchaud, Matteo Marsili, Jean-Pierre Nadal
Classical economics has developed an arsenal of methods, based on the idea of representative agents, to come up with precise numbers for next year's GDP, inflation and exchange rates, among (many) other things. Few, however, will disagree with the fact that the economy is a complex system, with a large number of strongly heterogeneous, interacting units of different types (firms, banks, households, public institutions) and different sizes. Now, the main issue in economics is precisely the emergent organization, cooperation and coordination of such a motley crowd of micro-units. Treating them as a unique ``representative'' firm or household clearly risks throwing the baby with the bathwater. As we have learnt from statistical physics, understanding and characterizing such emergent properties can be difficult. Because of feedback loops of different signs, heterogeneities and non-linearities, the macro-properties are often hard to anticipate. In particular, these situations generically lead to a very large number of possible equilibria, or even the lack thereof. Spin-glasses and other disordered systems give a concrete example of such difficulties. In order to tackle these complex situations, new theoretical and numerical tools have been invented in the last 50 years, including of course the replica method and replica symmetry breaking, and the cavity method, both static and dynamic. In this chapter we review the application of such ideas and methods in economics and social sciences. Of particular interest are the proliferation (and fragility) of equilibria, the analogue of satisfiability phase transitions in games and random economies, and condensation (or concentration) effects in opinion, wealth, etc
Claudia Voigt, Eric Werzner, Robert Fritzsch
et al.
The pressure drop of a ceramic foam filter is an important characteristic indicating the resistance to fluid flow through the filter. Filtration experiments have shown that filtration efficiency increases with decreasing functional pore size. However, this improvement comes at the cost of a higher pressure drop. Furthermore, trials with increased roughness of filter struts showed an improved filtration behavior. Comparing the influence of these filter properties on the filter efficiency is of high interest in terms of filtration per pressure drop. Therefore, the sensitivity of the pressure drop with respect to surface roughness needs to be known. In the study, the pressure drop of ceramic foam filters was measured for different functional pore sizes, porosities, and surface roughness in a water-based test facility at NTNU in Trondheim, Norway. The flow velocity was varied in the range of 0.6–80 cm/s, allowing the determination of the Darcy and non-Darcy permeability coefficients.