Structure deformation and curvature sensing of PIEZO1 in lipid membranes.

PIEZO channels respond to piconewton-scale forces to mediate critical physiological and pathophysiological processes1-5. Detergent-solubilized PIEZO channels form bowl-shaped trimers comprising a central ion-conducting pore with an extracellular cap and three curved and non-planar blades with intracellular beams6-10, which may undergo force-induced deformation within lipid membranes11. However, the structures and mechanisms underlying the gating dynamics of PIEZO channels in lipid membranes remain unresolved. Here we determine the curved and flattened structures of PIEZO1 reconstituted in liposome vesicles, directly visualizing the substantial deformability of the PIEZO1-lipid bilayer system and an in-plane areal expansion of approximately 300 nm2 in the flattened structure. The curved structure of PIEZO1 resembles the structure determined from detergent micelles, but has numerous bound phospholipids. By contrast, the flattened structure exhibits membrane tension-induced flattening of the blade, bending of the beam and detaching and rotating of the cap, which could collectively lead to gating of the ion-conducting pathway. On the basis of the measured in-plane membrane area expansion and stiffness constant of PIEZO1 (ref. 11), we calculate a half maximal activation tension of about 1.9 pN nm-1, matching experimentally measured values. Thus, our studies provide a fundamental understanding of how the notable deformability and structural rearrangement of PIEZO1 achieve exquisite mechanosensitivity and unique curvature-based gating in lipid membranes.

A qualitative study exploring nursing students' perspectives on and attitudes towards hospice care in China.

BACKGROUND: With the fast growth of the older population and the increasing rates of chronic illnesses, the demand for hospice care is increasing at a rapid pace. This is bringing great challenges to the healthcare system in China. Given that nursing students will be the main healthcare workforce in the future, and as such, have responsibilities to prepare for these challenges. Therefore, understanding nursing students' perspectives and attitudes towards hospice care in China is important to promote the development of hospice care services. OBJECTIVES: To explore the perspectives and attitudes of Chinese nursing students towards hospice care. METHOD: The descriptive phenomenology of a qualitative approach was used for the study. Data were collected through semi-structured individual interviews from 11 nursing students in China between April and June 2021. Data were analysed using Colaizzi's seven-step approach. FINDINGS: Three main themes were identified: (1) Lack of knowledge and skills; (2) lack of clinical experience; and (3) needs for service improvement. These findings indicated the problems of hospice care education and hospice care services in China. CONCLUSION: The nursing students in this study lacked theoretical knowledge and the practical skills of hospice care. This suggests that medical educational institutions and the government should take action to increase hospice care training for nursing students, in order to increase the capacity and availability of hospice care services. It also informs policy-makers, health professionals, and health educators about the further need for the development of hospice care services in China.

Molecular Dynamics Studies of Hydrogen Effect on Intergranular Fracture in α-Iron.

In the current study, the effect of hydrogen atoms on the intergranular failure of α-iron is examined by a molecular dynamics (MD) simulation. The effect of hydrogen embrittlement on the grain boundary (GB) is investigated by diffusing hydrogen atoms into the grain boundaries using a bicrystal body-centered cubic (BCC) model and then deforming the model with a uniaxial tension. The Debye Waller factors are applied to illustrate the volume change of GBs, and the simulation results suggest that the trapped hydrogen atoms in GBs can therefore increase the excess volume of GBs, thus enhancing intergranular failure. When a constant displacement loading is applied to the bicrystal model, the increased strain energy can barely be released via dislocation emission when H is present. The hydrogen pinning effect occurs in the current dislocation slip system, <111>{112}. The hydrogen atoms facilitate cracking via a decrease of the free surface energy and enhance the phase transition via an increase in the local pressure. Hence, the failure mechanism is prone to intergranular failure so as to release excessive pressure and energy near GBs. This study provides a mechanistic framework of intergranular failure, and a theoretical model is then developed to predict the intergranular cracking rate.