Si3N4/Graphene binary particles reinforced hybrid titanium composites and their characterization

This study reports on silicon nitride (Si3N4) and graphene nanoplatelets binary powder reinforced hybrid titanium composites obtained by a powder metallurgy method. Si3N4 powder was added at 3 wt.% and graphene nanoplatelets were added in various amounts (0.15, 0.30, 0.45, 0.60 wt.%) in the titanium matrix. Density, micro-Vickers hardness, compressive behavior, wear properties and microstructure of the hybrid composites were evaluated. Addition of different percentages of graphene nanoplatelets and 3 wt.% Si3N4 to the titanium matrix composites significantly enhanced mechanical properties. The highest hardness (634 HV) and compressive strength (1458 MPa) values were measured for 0.15 wt.% graphene nanoplatelets and 3 wt.% Si3N4 added titanium hybrid composite. The lowest mass loss and wear rate (Δm = 4 mg, W = 6.1×10–5 mm3 (N m)–1) values were measured for the same 0.15 wt.% graphene nanoplatelets and 3 wt.% Si3N4 added titanium hybrid composite compared with pure Ti.

Porosity Prediction from Gravity Inversion with Constraints from Resistivity Data

This work describes a method to carry out 2-D inversion of gravity data in terms of porosity and matrix density distribution using previous DC resistivity inversion results to constraint the fractional pore-water content in the rocks. The inversion is carried out using a controlled random search (CRS) algorithm for global optimization. The method was tested on synthetic data generated from a model representing a graben, and the results show that it can estimate accurate values of contrast-density and porosity. The method was also applied to gravity and dc experimental data collected in NE Portugal, showing results that agree quite well with the known geological information.

Extracellular matrix density regulates the formation of tumour spheroids through cell migration

In this work, we show how the mechanical properties of the cellular microenvironment modulate the growth of tumour spheroids. Based on the composition of the extracellular matrix, its stiffness and architecture can significantly vary, subsequently influencing cell movement and tumour growth. However, it is still unclear exactly how both of these processes are regulated by the matrix composition. Here, we present a centre-based computational model that describes how collagen density, which modulates the steric hindrance properties of the matrix, governs individual cell migration and, consequently, leads to the formation of multicellular clusters of varying size. The model was calibrated using previously published experimental data, replicating a set of experiments in which cells were seeded in collagen matrices of different collagen densities, hence producing distinct mechanical properties. At an initial stage, we tracked individual cell trajectories and speeds. Subsequently, the formation of multicellular clusters was also analysed by quantifying their size. Overall, the results showed that our model could accurately replicate what was previously seen experimentally. Specifically, we showed that cells seeded in matrices with low collagen density tended to migrate more. Accordingly, cells strayed away from their original cluster and thus promoted the formation of small structures. In contrast, we also showed that high collagen densities hindered cell migration and produced multicellular clusters with increased volume. In conclusion, this model not only establishes a relation between matrix density and individual cell migration but also showcases how migration, or its inhibition, modulates tumour growth.

Cementation exponent estimate in carbonate reservoirs: A new method

There are two approaches for measuring hydrocarbon saturation: well log interpretation and usually developed formulas. Archie’s equation is one of the most fundamental equations used for water saturation calculation. Archie’s equation includes three factors: cementation factor, tortuosity and saturation exponent. Archie determines these factors based on lab results in sandstone and provides fixed value for them. Carbonate reservoirs have a variety of textures, shapes and distribution of pores; therefore, the mentioned factors, especially cementation are not considered constant. In this study, the relationship between cementation factor and density log was examined because cementation factor is defined as a parameter that has a close relationship with density. By calculating the matrix density and accordance factor between the matrix density and cementation factor from core’s analysis, a log will be generated that can estimate the variation of cementation factor around the borehole. This method is useable for calculating the cementation factor in carbonate rocks. Keywords: Cementation factor, carbonate reservoir, density, new method, exponents.

Microstructure and Mechanical Properties of C/C Composites with Different Configuration of Unidirectional Macropores

The unidirectional porous C/C composites with different channel-diameter and channels-row spacing were prepared by a space-holder route. The effects of different channel-diameter and channels-row spacing on the mechanical properties and microstructures of the porous C/C composites were studied. Results show that increasing the channel-diameter or reducing the channels-row spacing helps to obtain finer PyC grains but significantly reduce the matrix density of the composites, and, in turn, the compressive strength of the composites. Porous C/C composites with lower porosity or higher density (e.g., S5,2) present relatively high strength, whereas C/C porous composites with lower density or higher porosity show a pseudo-plastic fracture mode and relatively lower strength. The compression strength in the load parallel to channel direction is higher than that in the load perpendicular to channel direction of the same composite.

Matrix density drives 3D organotypic lymphatic vessel activation in a microfluidic model of the breast tumor microenvironment

Lymphatic organotypic in vitro model allows the examination of components of the tumor microenvironment (e.g., ECM density, cancer cells) in lymphatic vessel biology in the context of cancer, providing insights into potential therapeutic targets.

Dendritic cell immune potency on 2D and in 3D collagen matrices

Dendritic cell immune potency from two immunologically relevant perspectives is modulated by cell culture dimensionality and collagen matrix density.

A TRACER culture invasion assay to probe the impact of cancer associated fibroblasts on head and neck squamous cell carcinoma cell invasiveness

A novel 3D in vitro co-culture platform to explore the interactions between cancer-associated fibroblasts and tumour cells that drive increased tumour cell invasion and the impact of matrix density.