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Evaporation driven buckling of a drop laden with graphene oxide nanosheets
Get PDFThe time-dependent shape of an evaporating spherical water drop containing graphene oxide (GO) nanosheets is measured for varying solid concentration, humidity level, and pH. The drop is sitting on a superhydrophobic surface, depinned from it. Three different stages of evaporation are identified: isotropic retraction of the drop interface, buckling of the shell of particles accumulated at the fluid interface, and shrinking of the buckled shell at constant shell shape. Marked differences between acidic and basic drops are reported. It is argued that this feature is caused by the pH-dependent interfacial adsorption of the GO particles. For intermediate values of GO concentration, dried capsules with remarkably repeatable folding patterns could be obtained, whose mode numbers are compatible with those predicted by an inertialess, linear elastic shell model. When redispersed in water, the dried capsules from acidic drops retain their shape better than capsules from basic drops.</p
Two-dimensional TiNBr as photocatalyst for overall water splitting
Get PDFTwo-dimensional (2D) Janus materials have gained increasing attention as water-splitting photocatalysts for hydrogen production. We use first-principles calculations to predict a stable 2D Janus T-TiNBr structure with strong near-ultraviolet sunlight absorption and band edges that align favorably with the water redox potentials for oxygen and hydrogen evolution. We show that the optical and electronic properties of T-TiNBr can be modulated to a certain extent by applying external uniaxial strain. Explicit calculations of the redox reactions reveal that solar-driven water splitting is viable at the N-side of T-TiNBr while the Br-side requires modifications such as vacancy creation, the application of an external potential, or adjustment of the pH conditions.</p
AFiD-Darcy:A finite difference solver for numerical simulations of convective porous media flows
Get PDFWe present an efficient solver for massively-parallel simulations of convective, wall-bounded and incompressible porous media flows. The algorithm consists of a second-order finite-difference pressure-correction scheme, allowing the use of an efficient FFT-based solver in problems with different boundary conditions. The parallelization method is implemented in a two-dimensional pencil-like domain decomposition, which enables efficient parallel large-scale simulations. The original version of the code presented by van der Poel et al. (2015) [35] has been modified to solve the Darcy equation for the momentum transport, representative of porous media flows driven by buoyancy. Two schemes are implemented to treat the diffusive term of the advection-diffusion equation, namely a fully implicit and semi-implicit formulation. Despite exhibiting a higher computational cost per time step, the fully implicit scheme allows an efficient simulation of transient flows, leading to a smaller time-to-solution compared to the semi-implicit scheme. The implementation was verified against different canonical flows, and the computational performance was examined. To show the code's capabilities, the maximal driving strength explored has been doubled as compared to state-of-art simulations, corresponding to an increase of the associated computational effort of about 8 to 16 times. Excellent strong scaling performance is demonstrated for both schemes developed and for domains with more than 1010 spatial degrees of freedom. Program summary: Program Title: AFiD-Darcy CPC Library link to program files: https://doi.org/10.17632/xhx3gzpj6n.1 Developer's repository link: https://github.com/depaolimarco/AFiD-Darcy Licensing provisions: CC BY 4.0 Programming language: Fortran 90, MPI External routines: FFTW3, HDF5 Nature of problem: Solving two- and three-dimensional Darcy equation coupled with a scalar field in a box bounded between two walls in one-direction and with periodic boundary conditions in the other two directions. Solution method: Second order finite difference method for spatial discretization, third order Runge–Kutta scheme in combination with Crank–Nicolson for the implicit terms for time advancement, two dimensional pencil distributed MPI parallelization. Implicit and semi-implicit formulations for the solution of the diffusive terms in the scalar transport equation.</p
Quantitative intra-arterial fluorescence angiography for direct monitoring of peripheral revascularization effects
Get PDFObjective: To investigate the feasibility of quantitative fluorescence angiography with intra-arterial dye injection (Q-iaFA) for intraoperative guidance during revascularization procedures in patients with chronic limb-threatening ischemia (CLTI). Methods: In this observational cohort study, 14 patients with CLTI undergoing endovascular intervention were included. Q-iaFA was performed directly before and after revascularization. The parameters time to peak (TTP) and normalized peak slope (PSnorm) were derived from intensity-time curves that were measured on the plantar side of the foot in five regions of interest. The main outcome was defined as the change in these Q-iaFA parameters between pre- and postoperative measurements in the region of interest with the most inferior preoperative value. Expected impact of revascularization was classified into strong, moderate or absent, based on intraoperative radiographic imaging and the Trans-Atlantic Inter-Society II standards. Results: Q-iaFA was successful without complications in all patients. Revascularization impact was classified as strong in 8 (57%), moderate in 5 (36%), and as absent in 1 (7%) patients. In the strong impact group, a significant decrease in TTP and increase in PSnorm was observed (P = .004). The same trend was less pronounced in the moderate impact group, without statistical significance (P = .104 and P = .094). Conversely, in the patient with no expected revascularization impact, TTP increased and PSnorm decreased. Conclusions: Q-iaFA is a feasible technique to evaluate peripheral tissue perfusion during vascular interventions. The extracted perfusion parameters are directly affected by revascularization of arterial lesions in patients with CLTI. This finding suggests that Q-iaFA may be useful to guide intraoperative decision making. Work is required to refine quantification strategies and relate Q-iaFA parameters to clinical outcomes.</p
Parametric Study and Optimization of a New Type of Solar Air Collector Employing Flat Micro Heat Pipe Arrays
No full textThe performance improvement of flat-plate solar air collectors (FPSACs) is vital for solar energy utilization. Accordingly, flat micro heat pipe arrays (FMHPAs) have been utilized in FPSACs given their excellent thermal conductivity and suitable specific surface area. To investigate the impact of structural parameters of the flat-plate solar air collector with flat micro heat pipe arrays and optimize the performance, this study establishes a CFD 3D model of the collector with L-shaped flat micro heat pipe arrays. Fin height H, fin spacing L, glass thickness D, and air gap thickness Sair are selected as four important structural parameters for numerical work. Response surface methodology is adopted to recognize the significance of each factor and realize the prediction and optimization of the collector’s thermal efficiency. Results show that the thermal efficiency can achieve a peak value of 52.50%. An enhanced heat transfer condition in condensation is obtained when the optimal fin height and fin spacing are 25 and 4 mm, respectively. Improved thermal insulation in evaporation is also achieved when the optimal glass thickness and air gap thickness are 3 and 35 mm, respectively. The significance order of the factors is H > L > D > Sair. The results can serve as an important reference for designing the flat-plate solar air collectors.</p
A comprehensive review of key technologies for the development of oil-free single screw compressors
No full textAs industries such as food, pharmaceuticals, electronics, and chemicals advance towards high-end refinement, there is an increasing demand for pure, oil-free compressed gas. This demand is driven by the need to ensure product quality, adhere to precision technology requirements, and strictly comply with production safety standards. Consequently, the trend towards using oil-free compressor is rapidly growing across various sectors. However, the majority of compressors labeled as “oil-free” are not entirely devoid of oil, as they still require bearing lubrication. Consequently, the advancement of water-lubricated oil-free compressors has emerged as a significant research focus for the future. Despite the evident performance benefits of oil-free single-screw compressors (SSCs), there is a scarcity of publicly available studies on this topic, and no comprehensive overview exists regarding the key technologies involved in the development of water-lubricated oil-free SSCs. This work aims to address this gap by synthesizing the limited public reports on the development of water-lubricated oil-free SSC technology. Additionally, it examines other relevant technologies that can inform the development of such compressors. The work provides a systematic overview of the basic performance modeling and prediction of water-lubricated oil-free SSCs, as well as the development of their key components. Finally, it offers forward-looking perspectives on the future development of this technology.</p
Impact of flooding on the social and mental health of older adults- A scoping review
Get PDFFlood disasters have a profound impact on the social and mental health of older adults. However, research on these effects remains limited, and a comprehensive understanding of their implications is lacking. This study addresses this gap through a scoping review of peer-reviewed literature, using the Disaster Pressure and Release model to analyze the vulnerabilities and risks older adults face during floods. Following PRISMA guidelines, we searched Web of Science, Scopus, and MEDLINE/PubMed in September 2022 and July 2024, identifying 6,492 studies. After screening and full-text review, 11 studies were included. The findings indicate that floods contribute to increased social isolation and limited social network support, and relatively fewer issues with a sense of place and belonging. Older adults also experience high levels of depression, anxiety, and PTSD, though sleep problems appear less common. With the low number of reviewed papers, findings highlight regional differences as significant gaps in current research. The study shows the need for better disaster preparedness strategies, stronger mental health support, and improved social help to mitigate the long-term effects of flooding on older adults. More research in different regions is important to create more effective policies and plans that meet the needs of older adults
Large-scale wave impact of a boiling liquid
Get PDFWave impact on solid structures is a well-studied phenomenon, but almost exclusively for the case that the impacting liquid (e.g. water) is surrounded by a non-condensable gas (such as air). In this study we turn to wave impact in a boiling liquid, a liquid that is in thermal equilibrium with its own vapour, which is of key relevance to the transport of cryogenic liquids, such as liquified natural gas and liquid hydrogen in the near future. More specifically, we use the Atmosphere facility at MARIN, NL, to prepare water/water vapour systems at different temperatures along the vapour curve. Here, we perform wave impact experiments by generating a soliton in a flume contained within the autoclave of the facility. A bathymetry profile interacts with the soliton, leading to a breaking wave that impacts onto a vertical wall, where we measure the pressures occurring during impact by means of embedded pressure sensors. In boiling liquids, we report wave impact pressures that are up to two orders of magnitude larger than those measured in comparable water-air experiments. We trace these pressures back to the collapse of the entrapped vapour pocket, which we semi-quantitatively describe using a simplified hemicylindrical vapour bubble model, which is in good agreement with the experimental findings. Finally, this allows us to predict the relevance of our findings for the transport of cryogenic liquids in huge overseas carriers where wave impact due to sloshing is the dominant cause of hydrodynamic load of containment systems in cargo tanks.</p
Advancing circulating tumor cell isolation and analysis:Development of optimized immunomagnetic techniques and molecular characterization approaches for early cancer detection
Get PDFCirculating tumor cells (CTCs) are critical to cancer metastasis and offer valuable insights for improving cancer diagnostics and personalized treatment strategies. This thesis addresses the main challenges in CTC isolation and analysis—low antigen expression, tumor heterogeneity, and molecular degradation—by developing innovative approaches to enhance capture efficiency, broaden detection range, and preserve cellular integrity for downstream applications.The research begins with a systematic evaluation of existing CTC isolation techniques and highlights their limitations, particularly in capturing heterogeneous CTC populations. To improve capture efficiency, various commercial streptavidin-coated magnetic beads are tested, identifying those around 100–150 nm as optimal. Building on this, custom-designed silica-coated magnetic nanobeads (NC@silica-SA) are synthesized, offering superior magnetic responsiveness and reduced non-specific binding. These advances significantly improve the isolation of CTCs, even those with low EpCAM expression.To address tumor heterogeneity, the study introduces a dual-targeting strategy combining recombinant VAR2CSA protein (rVAR2), which binds broadly to cancer cells, with anti-EpCAM antibodies. This approach increases the capture of diverse CTC populations across non-small-cell lung cancer lines. Additionally, fixation-free staining and isolation methods are developed to maintain RNA integrity, enabling reliable single-cell gene expression analyses. Together, these advancements enhance CTC detection, support more accurate molecular profiling, and open new avenues for personalized cancer care
Re-think” sulfur curing – part 1
Get PDFSince Charles Goodyear discovered the sulfur curing of NR in 1839, many studies were carried out to understand its mechanism. Nowadays, the broadly accepted mechanism includes an activated accelerator Zn-complex which enables sulfur coupling to the polymer in the allylic position to the double bond. Modern passenger car tire treads do not contain any longer Natural Rubber but a blend of SSBR and BR, filled with a silica /silane system. Is it possible to transfer all in NR gained knowledge to such a modern passenger car tire tread formulation or is it required to “re-think” sulfur curing?<br/