405905 research outputs found
Sort by
The bacterial ESCRT-III PspA rods thin lipid tubules and increase membrane curvature through helix α0 interactions
No full textThe phage shock protein A (PspA), a bacterial member of the endosomal sorting complexes required for transport (ESCRT)-III superfamily, forms rod-shaped helical assemblies that internalize membrane tubules. The N-terminal helix α0 of PspA (and other ESCRT-III members) has been suggested to act as a membrane anchor; the detailed mechanism, however, of how it binds to membranes and eventually triggers membrane fusion and/or fission events remains unclear. By solving a total of 15 cryoelectron microscopy (cryo-EM) structures of PspA and a truncation lacking the N-terminal helix α0 in the presence of Escherichia coli polar lipid membranes, we show in molecular detail how PspA interacts with and remodels membranes: Binding of the N-terminal helix α0 in the outer tubular membrane leaflet induces membrane curvature, supporting membrane tubulation by PspA. Detailed molecular dynamics simulations and free energy computations of interactions between the helix α0 and negatively charged membranes suggest a compensating mechanism between helix-membrane interactions and the energy contributions required for membrane bending. The energetic considerations are in line with the membrane structures observed in the cryo-EM images of tubulated membrane vesicles, fragmented vesicles inside tapered PspA rods, and shedded vesicles emerging at the thinner PspA rod ends. Our results provide insights into the molecular determinants and a potential mechanism of vesicular membrane remodeling mediated by a member of the ESCRT-III superfamily
Encoding the boosting of collagen gel stiffness as induced by mechanical perturbation during maturation
No full textAn integrated scheduling and control scheme with two economic layers for demand side management of chemical processes
No full textReactive transport modeling of radium transport and co-precipitation in fractured crystalline rocks
No full text
Atomic layer deposition (ALD)
No full textM III.1: Functional Layers - Atomic Layer Deposition(ALD)Vera Barysch (Supervisor: Shicheng Yu)IntroductionAtomic layer deposition (ALD) is a thin-film growth method in which a substrate is first exposedto a gaseous reactant that chemisorbs onto its surface. After purging excess reactant and byproducts,a second gaseous reactant is introduced, reacting with the first layer to form a solid film(Figure 1). By repeating this cycle, the film thickness can be increased with atomic-scale precision.This self-limiting growth mechanism enables precise control over layer thickness and conformality,even on complex 3D surfaces.[1]Figure 3: Schematic depiction of the ALD process. The cycle can be repeated until the desired layer thickness is achieved. [2]The main drawbacks of ALD are its low throughput and relatively high production costs, whichinitially limited its use in functional coatings. However, with the continuing miniaturization ofelectronic devices following Moore’s law, precise nanoscale control has become increasinglyimportant, paving the way for broader ALD adoption. In contrast to chemical vapor deposition(CVD) or sputtering, ALD offers better uniformity and conformality.[1]ApplicationsSince its introduction by Aleskovski in Russia and subsequent commercial development bySuntola et al. in Finland, ALD has been applied in the fabrication of optical devices,semiconductors, and other electronics, as well as in catalysis and anti-corrosion coatings. Inelectrochemical energy systems, notable applications include:- LTO-coated LLZTO solid electrolytes: Li6.45 Al0.05La3Zr1.6Ta0.4O12(LLZTO) was coatedwith nanoscale Li4Ti5O12 (LTO) via TiO2 ALD, reducing grain boundary resistance andimproving Li wettability.[3]- Single-atom Pt catalysts: ALD enables the preparation of Pt single-atom catalysts withhigh catalytic efficiency for the hydrogen evolution reaction.[4]- Gas separation membranes: ALD coatings of Al2O3, ZnO, or TiO2 on polymermembranes modify the microstructure, resulting in tunable CO2 permeation behavior.[5]ALD variantsThermal ALD relies on heat to drive the surface reactions. Plasma-enhanced ALD (PEALD) usesa plasma source to generate reactive species, enabling deposition at lower temperatures and oftenincreasing reaction rates. Radical-enhanced ALD (REALD) similarly introduces highly reactiveradicals, but without the ion bombardment associated with plasma, which can be advantageous forsensitive substrates. More recently, continuous flow ALD has been developed for industrialscalability: in this approach, substrates pass sequentially through dedicated chambers for precursorexposure and purging under constant flow conditions.[1]Questions1. What are the main advantages and limitations of ALD?2. How is ALD relevant to energy research?References[1] Kääriäinen, T., et al., John Wiley & Sons 2013.[2] Seo, J., et al., Nanoscale Adv. 4 2022 1060.[3] Chang, C.-Y., et al., J. Power Sources 652 2025 237593.[4] Cheng, N., et al., Nat. Commun. 7 2016 13638.[5] Niu, X., et al., J. Membr. Sci. 664 2022 121103
