Protein adsorption and interfacial rheology interfering in dilatational experiment

The static and dilatational response of β-lactoglobulin fibrils and native β-lactoglobulin (monomers) at water-air and water-oil interfaces (pH 2) was measured using the pendant drop method. The resulting adsorption behavior and viscoelasticity is dependent of concentration and adsorption time. The interfacial pressure of the β-lactoglobulin fibrils obtained in static measurements was 16-18 mN/m (against air) and 7 mN/m (against oil) for all concentrations. With higher concentrations, faster adsorption kinetics and slightly higher interfacial and surface pressure is achieved but did not lead to higher viscoelastic moduli. The transient saturation of the interface is similar for both the fibril solution and the monomers, however the fibril solution forms a strong viscoelastic network. To evaluate the superimposed adsorption behavior and rheological properties, the formed interfacial layer was subjected to dilatational experiments, which were performed by oscillating the surface area of the drop in sinusoidal and sawtooth (diagonal) deformation manner. The sinusoidal oscillations (time depended area deformation rate) result in a complex interfacial tension behavior against air and oil interfaces and show remarkable differences during compression and expansion as emphasized by Lissajous figures. For diagonal (constant area deformation rate) experiments, a slight bending of the interfacial tension response was observed at low frequencies emphasizing the influence of protein adsorption during rheological measurement

Lipid emulsion interfacial design modulates human in vivo digestion and satiation hormone response

\ua9 2022 The Royal Society of Chemistry. Lipid emulsions (LEs) with tailored digestibility have the potential to modulate satiation or act as delivery systems for lipophilic nutrients and drugs. The digestion of LEs is governed by their interfacial emulsifier layer which determines their gastric structuring and accessibility for lipases. A plethora of LEs that potentially modulate digestion have been proposed in recent years, however, in vivo validations of altered LE digestion remain scarce. Here, we report on the in vivo digestion and satiation of three novel LEs stabilized by whey protein isolate (WPI), thermo-gelling methylcellulose (MC), or cellulose nanocrystals (CNCs) in comparison to an extensively studied surfactant-stabilized LE. LE digestion and satiation were determined in terms of gastric emptying, postprandial plasma hormone and metabolite levels characteristic for lipid digestion, perceived hunger/fullness sensations, and postprandial food intake. No major variations in gastric fat emptying were observed despite distinct gastric structuring of the LEs. The plasma satiation hormone and metabolite response was fastest and highest for WPI-stabilized LEs, indicating a limited capability of proteins to prevent lipolysis due to fast hydrolysis under gastric conditions and displacement by lipases. MC-stabilized LEs show a similar gastric structuring as surfactant-stabilized LEs but slightly reduced hormone and metabolite responses, suggesting that thermo-gelling MC prevents lipase adsorption more effectively. Ultimately, CNC-stabilized LEs showed a drastic reduction (>70%) in plasma hormone and metabolite responses. This confirms the efficiency of particle (Pickering) stabilized LEs to prevent lipolysis proposed in literature based on in vitro experiments. Subjects reported more hunger and less fullness after consumption of LEs stabilized with MC and CNCs which were able to limit satiation responses. We do not find evidence for the widely postulated ileal brake, i.e. that delivery of undigested nutrients to the ileum triggers increased satiation. On the contrary, we find decreased satiation for LEs that are able to delay lipolysis. No differences in food intake were observed 5 h after LE consumption. In conclusion, LE interfacial design modulates in vivo digestion and satiation response in humans. In particular, Pickering LEs show extraordinary capability to prevent lipolysis and qualify as oral delivery systems for lipophilic nutrients and drugs

Surgical fixation of distal ulna neck and head fractures

Objectives: Distal ulna plate fixation for ulnar neck and head fractures (excluding ulnar styloid fractures) aims to anatomically reduce the distal ulna fracture (DUF) by open reduction and internal fixation, while obtaining a stable construct allowing functional rehabilitation without need for cast immobilization. Indications: Severe displacement, angulation or translation, as well as unstable or intra-articular fractures. Furthermore, multiple trauma or young patients in need of quick functional rehabilitation. Contraindications: Inability to surgically address concomitant ipsilateral extremity fractures, thus, limiting early active rehabilitation. Stable, nondisplaced fractures. Need for bridging plate or external fixator of distal radiocarpal joint. Surgical technique: An ulnar approach, with a straight incision between the extensor and flexor carpi ulnaris. Preservation of the dorsal branch of the ulnar nerve. Reduction and plate fixation with avoidance of plate impingement in the articular zone. Postoperative management: Postoperatively, an elastic bandage is applied for the first 24–48 h. In isolated DUF with stable fixation, a postoperative splint is often unnecessary and should be avoided. For the first four weeks, only light weightbearing of everyday activities is allowed to protect the osteosynthesis. Thereafter, heavier weightbearing and activities are allowed and can be increased as tolerated. Results: The best available evidence likely shows that for younger patients with a DUF, with or without concomitant distal radius fractures, open reduction and internal fixation can be safely achieved with good functional outcome and acceptable union and complication rates as long as proper technique is ensured

Protein adsorption and interfacial rheology interfering in dilatational experiment

The static and dilatational response of β-lactoglobulin fibrils and native β-lactoglobulin (monomers) at water-air and water-oil interfaces (pH 2) was measured using the pendant drop method. The resulting adsorption behavior and viscoelasticity is dependent of concentration and adsorption time. The interfacial pressure of the β-lactoglobulin fibrils obtained in static measurements was 16–18 mN/m (against air) and 7 mN/m (against oil) for all concentrations. With higher concentrations, faster adsorption kinetics and slightly higher interfacial and surface pressure is achieved but did not lead to higher viscoelastic moduli. The transient saturation of the interface is similar for both the fibril solution and the monomers, however the fibril solution forms a strong viscoelastic network. To evaluate the superimposed adsorption behavior and rheological properties, the formed interfacial layer was subjected to dilatational experiments, which were performed by oscillating the surface area of the drop in sinusoidal and sawtooth (diagonal) deformation manner. The sinusoidal oscillations (time depended area deformation rate) result in a complex interfacial tension behavior against air and oil interfaces and show remarkable differences during compression and expansion as emphasized by Lissajous figures. For diagonal (constant area deformation rate) experiments, a slight bending of the interfacial tension response was observed at low frequencies emphasizing the influence of protein adsorption during rheological measurements

Blocking Gastric Lipase Adsorption and Displacement Processes with Viscoelastic Biopolymer Adsorption Layers

International audienc

Blocking Gastric Lipase Adsorption and Displacement Processes with Viscoelastic Biopolymer Adsorption Layers

International audienc

Evaporative cooling for polymer electrolyte fuel cells - An operando analysis at technical single cell level

Evaporative cooling has the potential to reduce stack and system volume of polymer electrolyte fuel cells by up to 30% and to cut costs significantly by simplifying the multi-layered structure of bipolar plates and eliminating the need for external humidification. This study provides an experimental proof of concept by analyzing the evaporation behavior, cooling power, internal humidification, electrochemical performance and operational stability of evaporative cooling under technical cell boundary conditions. Isothermal in situ as well as operando studies are carried out in an evaporatively cooled fuel cell (15 cm2 active area, 80 °C, ambient pressure). Relative humidity boundary conditions imitate the inlet, center and outlet of a technical cell. Main findings show that the evaporation rate is saturation limited at low gas velocities, whereas it is transport limited at higher gas speed. Operando measurements prove that evaporative cooling works at a technical cell level with multiple water supply lines. The entire waste heat is removed and sufficient membrane humidification is achieved when dry inlet gases are used. Furthermore, it is shown that optimal performance is achieved in a counter-flow arrangement. The observed electrochemical performance is comparable to conventional cooling with humidified gases at inlet, center and outlet of the cell.ISSN:0378-7753ISSN:1873-275