Water freezing remains a perennial topic of great relevance to many important aspects of our lives; from the climate to human society and from economics to medicine, frozen water profoundly ...influences our living environment and life activities. There have been numerous publications on water freezing; however, confusion regarding the process of freezing remains. In this review, we mainly focused on the nucleation aspects of water freezing; in particular, we focused on the effect of the surface morphology and nanostructure of foreign bodies. This review covers the recent progress in ice nucleation and anti-freezing strategies within the framework of nucleation principles. In this regard, we first summarize the crystal nucleation theories. Due to high interfacial energy, ice crystallization is primarily controlled by heterogeneous nucleation events, because the homogeneous nucleation barrier of ice is extremely high. In addition to the interfacial energy, the interfacial morphology or nanostructure of foreign bodies plays a diverse role under different supercooling regimes due to the Gibbs-Thomson effect. This effect gives rise to the inverse homogeneous-like nucleation phenomenon, in which foreign bodies have little influence on the nucleation barrier. This ensures the accurate measurement of the nucleation barrier, critical size, and water-ice interfacial energy, in agreement with the latest studies based on a microemulsions approach, metadynamics, the mW model,
etc.
As a consequence, anti-freezing strategies can be implemented by reducing the nucleation rate through restriction of the contact area of the water/substrate interface, by increasing the heterogeneous nucleation barrier through modification of the interfacial properties of foreign particles, including the interfacial structure and the interaction between the water and foreign particles and by kink kinetics. Within this context, the anti-freezing mechanism of superhydrophobic substrates was reviewed. Therefore, it follows that by significantly reducing the contact area between the water and substrate, superhydrophobic materials can effectively reduce the heterogeneous nucleation rate. We hope that this review will provide a unified picture and guidance for future work on water freezing.
Water freezing remains a perennial topic of great relevance to many important aspects of our lives; from the climate to human society and from economics to medicine, frozen water profoundly influences our living environment and life activities.
Terahertz (THz = 1012 Hz) radiation has attracted wide attention for its unprecedented sensing ability and its noninvasive and nonionizing properties. Tremendous strides in THz instrumentation have ...prompted impressive breakthroughs in THz biomedical research. Here, we review the current state of THz spectroscopy and imaging in various biomedical applications ranging from biomolecules, including DNA/RNA, amino acids/peptides, proteins, and carbohydrates, to cells and tissues. We also address the potential biological effects of THz radiation during its biological applications and propose future prospects for this cutting-edge technology.
To determine distribution of severe acute respiratory syndrome coronavirus 2 in hospital wards in Wuhan, China, we tested air and surface samples. Contamination was greater in intensive care units ...than general wards. Virus was widely distributed on floors, computer mice, trash cans, and sickbed handrails and was detected in air ≈4 m from patients.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A comprehensive review on the five levels of hierarchical structures of silk materials and the correlation with macroscopic properties/performance of the silk materials, that is, the toughness, ...strain‐stiffening, etc., is presented. It follows that the crystalline binding force turns out to be very important in the stabilization of silk materials, while the β‐crystallite networks or nanofibrils and the interactions among helical nanofibrils are two of the most essential structural elements, which to a large extent determine the macroscopic performance of various forms of silk materials. In this context, the characteristic structural factors such as the orientation, size, and density of β‐crystallites are very crucial. It is revealed that the formation of these structural elements is mainly controlled by the intermolecular nucleation of β‐crystallites. Consequently, the rational design and reconstruction of silk materials can be implemented by controlling the molecular nucleation via applying sheering force and seeding (i.e., with carbon nanotubes). In general, the knowledge of the correlation between hierarchical structures and performance provides an understanding of the structural reasons behind the fascinating behaviors of silk materials.
This review presents five levels of hierarchical structures associated with the mechanical performance of silk materials. The crystallization mechanism concerning how silk fibroin molecules self‐organize into crystallites and crystal networks is highlighted, which allows for rational design and sheds light on mesoscopic reconstruction and mesoscopic engineering for synthesizing mechanically enhanced silk materials.
Silk fibroin (SF) has attracted great interest in bone tissue engineering due to its extraordinary characteristics in terms of mechanical properties, biocompatibility, and biodegradability. SF ...scaffolds are assembled by biocompatible polydopamine nanoparticles at mesoscopic scale, which endows the scaffolds with a near‐infrared (NIR) light response for the treatment of bone tumors. The functionalized SF scaffold not only enhances the significant structure and performance of native SF scaffold for bone treatment and reconstruction, such as primary and mesoscopic structure, multi‐level pores, and biodegradation, as well as biocompatibility but also have excellent photothermal effect leading a significant cytotoxicity to MG63 cancer cells after NIR laser irradiation. Moreover, the penetration of NIR light in tissue is improved using an optical fiber, which demonstrates the obtained scaffolds’ great potential in the application of photothermal therapy.
Polydopamine nanoparticles functionalized silk fibroin (PDA@SF) scaffolds are endowed with high photothermal efficiency, outstanding biocompatibility, controllable mechanical properties, and degradation performance to realize both the killing of bone tumor cells and the repairing of bone defects, which are potential candidates for bone tumor therapy.
Silk protein is one of the a promising materials for on‐skin and implantable electronic devices due to its biodegradability and biocompatibility. However, its intrinsic brittleness as well as poor ...thermal stability limits its applications. In this work, robust and heat‐resistant silk fibroin composite membranes (SFCMs) are synthesized by mesoscopic doping of regenerated silk fibroin (SF) via the strong interactions between SF and polyurethane. Surprisingly, the obtained SFCMs can endure the tensile test (>200%) and thermal treatment (up to 160 °C). Attributed to these advantages, traditional micromachining techniques, such as inkjet printing, can be carried out to print flexible circuits on such protein substrate. Based on this, Ag nanofibers (NFs) and Pt NFs networks are successfully constructed on both sides of the SFCMs to function as heaters and temperature sensors, respectively. Furthermore, the integrated protein‐based electronic skin (PBES) exhibits high thermal stability and temperature sensitivity (0.205% °C−1). Heating and temperature distribution detection are realized by array‐type PBES, contributing to potential applications in dredging of the blood vessel for alleviating arthritis. This PBES is also inflammation‐free and air‐permeable so that it can directly be laminated onto human skin for long‐term thermal management.
Silk fibroin composite membranes with excellent extensibility, highly heat‐resistant ability, air permeability, biocompatibility, and degradability are candidates for electronic skins (E‐skins) applied in healthcare. Due to these abilities, E‐skins can be mounted onto human skin, thereby simultaneously realizing heating and array‐type temperature detection, even for on‐skin camouflage.
The rapid outbreak of coronavirus disease 2019 (COVID-19) has been a matter of international concern as the disease is spreading fast 1, 2. Considering that the contagious disease has led to an ...enormous impact globally, there is an urgent need to identify the risk populations with poor prognosis. Ageing is associated with certain changes in pulmonary physiology, pathology and function, during the period of lung infection. Therefore, age-related differences in responsiveness and tolerance become obvious and lead to worse clinical outcomes in elderly individuals 3. Previous studies have mentioned that older COVID-19 patients are at an increased risk of death 4–7. However, the age-related clinical characteristics, disease courses and outcomes other than death in COVID-19 patients remain unclear.
Age significantly determined the clinical features and prognosis of COVID-19. The prognosis was worse in patients older than 60 years, calling for clinicians to pay more attention to patients of this age.
https://bit.ly/34DTI05
Due to the natural biodegradability and biocompatibility, silk fibroin (SF) is one of the ideal platforms for on‐skin and implantable electronic devices. However, the development of SF‐based ...electronics is still at a preliminary stage due to the SF film intrinsic brittleness as well as the solubility in water, which prevent the fabrication of SF‐based electronics through traditional techniques. In this article, a flexible and stretchable silver nanofibers (Ag NFs)/SF based electrode is synthesized through water‐free procedures, which demonstrates outstanding performance, i.e., low sheet resistance (10.5 Ω sq−1), high transmittance (>90%), excellent stability even after bending cycles >2200 times, and good extensibility (>60% stretching). In addition, on the basis of such advanced (Ag NFs)/SF electrode, a flexible and tactile sensor is further fabricated, which can simultaneously detect pressure and strain signals with a large monitoring window (35 Pa–700 kPa). Besides, this sensor is air‐permeable and inflammation‐free, so that it can be directly laminated onto human skins for long‐term health monitoring. Considering the biodegradable and skin‐comfortable features, this sensor may become promising to find potential applications in on‐skin or implantable health‐monitoring devices.
A biodegradable and stretchable protein‐based sensor with good biocompatibility and high response time is fabricated. It can be used for the human motion detection, such as arm bending and laryngeal movement.
In the early stages of the outbreak of coronavirus disease 2019 (COVID-19) in Hubei, China, the local health-care system was overwhelmed. Physicians and nurses who had no infectious disease expertise ...were recruited to provide care to patients with COVID-19. To our knowledge, no studies on their experiences of combating COVID-19 have been published. We aimed to describe the experiences of these health-care providers in the early stages of the outbreak.
We did a qualitative study using an empirical phenomenological approach. Nurses and physicians were recruited from five COVID-19-designated hospitals in Hubei province using purposive and snowball sampling. They participated in semi-structured, in-depth interviews by telephone from Feb 10 to Feb 15, 2020. Interviews were transcribed verbatim and analysed using Haase's adaptation of Colaizzi's phenomenological method.
We recruited nine nurses and four physicians. Three theme categories emerged from data analysis. The first was “being fully responsible for patients' wellbeing—‘this is my duty’”. Health-care providers volunteered and tried their best to provide care for patients. Nurses had a crucial role in providing intensive care and assisting with activities of daily living. The second category was “challenges of working on COVID-19 wards”. Health-care providers were challenged by working in a totally new context, exhaustion due to heavy workloads and protective gear, the fear of becoming infected and infecting others, feeling powerless to handle patients' conditions, and managing relationships in this stressful situation. The third category was “resilience amid challenges”. Health-care providers identified many sources of social support and used self-management strategies to cope with the situation. They also achieved transcendence from this unique experience.
The intensive work drained health-care providers physically and emotionally. Health-care providers showed their resilience and the spirit of professional dedication to overcome difficulties. Comprehensive support should be provided to safeguard the wellbeing of health-care providers. Regular and intensive training for all health-care providers is necessary to promote preparedness and efficacy in crisis management.
National Key R&D Program of China, Project of Humanities and Social Sciences of the Ministry of Education in China.
•Medical staff experience mental health disturb during the COVID-19 pandemic.•Direct and indirect exposure to COVID-19 affects the mental health profoundly.•Psychological materials and resources ...provide some protection.•Interventions with appropriate level are urgent.
The severe 2019 outbreak of novel coronavirus disease (COVID-19), which was first reported in Wuhan, would be expected to impact the mental health of local medical and nursing staff and thus lead them to seek help. However, those outcomes have yet to be established using epidemiological data. To explore the mental health status of medical and nursing staff and the efficacy, or lack thereof, of critically connecting psychological needs to receiving psychological care, we conducted a quantitative study. This is the first paper on the mental health of medical and nursing staff in Wuhan. Notably, among 994 medical and nursing staff working in Wuhan, 36.9% had subthreshold mental health disturbances (mean PHQ-9: 2.4), 34.4% had mild disturbances (mean PHQ-9: 5.4), 22.4% had moderate disturbances (mean PHQ-9: 9.0), and 6.2% had severe disturbance (mean PHQ-9: 15.1) in the immediate wake of the viral epidemic. The noted burden fell particularly heavily on young women. Of all participants, 36.3% had accessed psychological materials (such as books on mental health), 50.4% had accessed psychological resources available through media (such as online push messages on mental health self-help coping methods), and 17.5% had participated in counseling or psychotherapy. Trends in levels of psychological distress and factors such as exposure to infected people and psychological assistance were identified. Although staff accessed limited mental healthcare services, distressed staff nonetheless saw these services as important resources to alleviate acute mental health disturbances and improve their physical health perceptions. These findings emphasize the importance of being prepared to support frontline workers through mental health interventions at times of widespread crisis.
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