Critical Casimir forces and colloidal aggregation: A numerical study

We present a numerical study of the effective potential $V_\mathrm{eff}$ between two hard-sphere colloids dispersed in a solvent of interacting particles, for several values of temperature and solvent density, approaching the solvent gas-liquid critical point. We investigate the stability of a system of particles interacting via $V_\mathrm{eff}$ to evaluate the locus of colloidal aggregation in the solvent phase-diagram, and its dependence on the colloid size. We assess how the excluded volume depletion forces are modified by solvent attraction and discuss under which conditions solvent critical fluctuations, in the form of critical Casimir forces, can be used to effectively manipulate colloidal aggregation

3D bioprinting of multifunctional alginate dialdehyde (ADA)–gelatin (GEL) (ADA-GEL) hydrogels incorporating ferulic acid

: The present work explores the 3D extrusion printing of ferulic acid (FA)-containing alginate dialdehyde (ADA)-gelatin (GEL) scaffolds with a wide spectrum of biophysical and pharmacological properties. The tailored addition of FA (≤0.2 %) increases the crosslinking between FA and GEL in the presence of calcium chloride (CaCl2) and microbial transglutaminase, as confirmed using trinitrobenzenesulfonic acid (TNBS) assay. In agreement with an increase in crosslinking density, a higher viscosity of ADA-GEL with FA incorporation was achieved, leading to better printability. Importantly, FA release, enzymatic degradation and swelling were progressively reduced with an increase in FA loading to ADA-GEL, over 28 days. Similar positive impact on antibacterial properties with S. epidermidis strains as well as antioxidant properties were recorded. Intriguingly, FA incorporated ADA-GEL supported murine pre-osteoblast proliferation with reduced osteosarcoma cell proliferation over 7 days in culture, implicating potential anticancer property. Most importantly, FA-incorporated and cell-encapsulated ADA-GEL can be extrusion printed to shape fidelity-compliant multilayer scaffolds, which also support pre-osteoblast cells over 7 days in culture. Taken together, the present study has confirmed the significant potential of 3D bioprinting of ADA-GEL-FA ink to obtain structurally stable scaffolds with a broad spectrum of biophysical and therapeutically significant properties, for bone tissue engineering applications

Development of a Multi-Channel Transmit Extension for a Broadband RF-Electronics and its Evaluation on a 9.4 T Animal Scanner with 8 Transmit Channels

In the last years the concept of parallel RF transmission has gained considerable interest, especially in the domain of high field MRI. In essence two principal application domains have emerged from this concept: the field of static B1-inhomogeneity compensation, also known as B1-shimming [1,2,3], and the technique of accelerated spatially-selective excitation (SSE), also known as Parallel Excitation (PEX) or Transmit SENSE [4,5], for improving the performance of many useful applications of SSE such as inner-volume imaging or targeted spectroscopy. In the field of B1-shimming the demands on the RF system are moderate. The RF system must only be capable of generating the same RF pulse on different channels with individual, but time-constant amplitude scaling and phase offsets. This can be realized by RF splitters, amplitude modulators and phase shifters. In contrast, to perform PEX-experiments the RF system must be capable of generating different complex RF waveforms on multiple transmit channels with high accuracy. Recently, several experimental studies of PEX with 4 and 8 transmit channels have been performed [6,7,8] and it has been shown that for doing PEX with high spatial resolution and high acceleration factors, the RF system must be equipped with a sufficient number of transmit channels. Therefore, the aim of this work was to develop a multichannel transmit extension for a broadband RF electronics with the potential of driving large numbers of transmit channels and to implement this electronics concept on a 9.4 T animal scanner with 8 transmit and receive channels