The most important properties of self‐healing polymers are efficient recovery at room temperature and prolonged durability. However, these two characteristics are contradictory, making it difficult ...to optimize them simultaneously. Herein, a transparent and easily processable thermoplastic polyurethane (TPU) with the highest reported tensile strength and toughness (6.8 MPa and 26.9 MJ m−3, respectively) is prepared. This TPU is superior to reported contemporary room‐temperature self‐healable materials and conveniently heals within 2 h through facile aromatic disulfide metathesis engineered by hard segment embedded aromatic disulfides. After the TPU film is cut in half and respliced, the mechanical properties recover to more than 75% of those of the virgin sample within 2 h. Hard segments with an asymmetric alicyclic structure are more effective than those with symmetric alicyclic, linear aliphatic, and aromatic structures. An asymmetric structure provides the optimal metathesis efficiency for the embedded aromatic disulfide while preserving the remarkable mechanical properties of TPU, as indicated by rheological and surface investigations. The demonstration of a scratch‐detecting electrical sensor coated on a tough TPU film capable of auto‐repair at room temperature suggests that this film has potential applications in the wearable electronics industry.
Remarkably tough and room‐temperature self‐healable thermoplastic polyurethane (TPU) elastomers are engineered by hard segment embedding aromatic disulfides. Hard segments with asymmetric alicyclic structure have adequate packing density to achieve efficient self‐healing and to retain the remarkable mechanical properties of TPU. Their toughness value of 26.9 MJ m−3 doubles previous records. A scratch‐detecting and auto‐repairing electrical sensor application is demonstrated.
•Reviewed 572 papers on maritime accidents from 125 journals in English.•Analyzed author location, discipline, research focus, methods and data in 50 years.•The focus shifts from naval technology to ...human errors and socio-economic factors.•Future studies will be more inter- & multi-disciplinary with multiple data sources.
Over the past 50 years, research in maritime accidents has undergone a series of fundamental changes. Understanding the evolution of these changes can help maritime communities to know what has been done in the past, how maritime safety can be improved in the future, and how to reduce or eliminate the risks to ships, the lives aboard them, the cargo they carry, and the marine environment.
This study conducts a comprehensive literature review on research in maritime accidents, comprising 572 papers published in 125 journals over the 50 years from 1965 to 2014. The patterns of evolution of the researchers, the journals, the disciplines involved, the research methods, the major issues and causes, and the data sources are identified, and the changes explained. We find that the main focus of research in maritime accidents has shifted over the past 50 years from naval architecture to human error, and may continue to expand into socio-economic factors. In addition, future research in maritime accidents will be multi-disciplinary, use multiple data sources, and adopt advanced research methods, to account for complex interactions between the natural environment, the development of naval technology, human behavior, and shipping market conditions.
Environmental and health concerns force the search for sustainable super engineering plastics (SEPs) that utilise bio-derived cyclic monomers, e.g. isosorbide instead of restricted petrochemicals. ...However, previously reported bio-derived thermosets or thermoplastics rarely offer thermal/mechanical properties, scalability, or recycling that match those of petrochemical SEPs. Here we use a phase transfer catalyst to synthesise an isosorbide-based polymer with a high molecular weight >100 kg mol
, which is reproducible at a 1-kg-scale production. It is transparent and solvent/melt-processible for recycling, with a glass transition temperature of 212 °C, a tensile strength of 78 MPa, and a thermal expansion coefficient of 23.8 ppm K
. Such a performance combination has not been reported before for bio-based thermoplastics, petrochemical SEPs, or thermosets. Interestingly, quantum chemical simulations show the alicyclic bicyclic ring structure of isosorbide imposes stronger geometric restraint to polymer chain than the aromatic group of bisphenol-A.
BACKGROUND:The morbidity and mortality of patients with functional mitral regurgitation (MR) remain high, but no pharmacological therapy has been proven effective. The hypothesis of this study was ...that sacubitril/valsartan would be superior to valsartan alone in improving functional MR via dual inhibition of the renin-angiotensin system and neprilysin.
METHODS:In this double-blind trial, we randomly assigned 118 patients with heart failure with chronic functional MR secondary to left ventricular (LV) dysfunction to receive either sacubitril/valsartan or valsartan, in addition to standard medical therapy for heart failure. The primary end point was the change in effective regurgitant orifice area of functional MR from baseline to the 12-month follow-up. Secondary end points included changes in regurgitant volume, LV end-systolic volume, LV end-diastolic volume, and incomplete mitral leaflet closure area.
RESULTS:The decrease in effective regurgitant orifice area was significantly greater in the sacubitril/valsartan group than in the valsartan group (–0.058±0.095 versus –0.018±0.105 cm; P=0.032) in an intention-to-treat analysis including 117 (99%) patients. Regurgitant volume was also significantly decreased in the sacubitril/valsartan group in comparison with the valsartan group (mean difference, –7.3 mL; 95% CI, –12.6 to –1.9; P=0.009). There were no significant between-group differences regarding the changes in incomplete mitral leaflet closure area and LV volumes, with the exception of LV end-diastolic volume index (P=0.044). We noted no significant difference in the change of blood pressure between the treatment groups, and 7 patients (12%) in the sacubitril/valsartan group and 9 (16%) in the valsartan group had ≥1 serious adverse events (P=0.54).
CONCLUSIONS:Among patients with secondary functional MR, sacubitril/valsartan reduced MR to a greater extent than did valsartan. Our findings suggest that an angiotensin receptor-neprilysin inhibitor might be considered for optimal medical therapy of patients with heart failure and functional MR.
CLINICAL TRIAL REGISTRATION:URLhttps://www.clinicaltrials.gov. Unique identifierNCT02687932.
Cation exchange membranes (CEMs) have attracted tremendous attention in electrochemical energy conversion and storage systems owing to their high proton conductivity and chemical stability. However, ...applications of CEMs suffer from a number of disadvantages such as requirement of costly platinum catalyst, and high crossover of fuels or positively charged redox species due to the electro-osmotic drag. Anion exchange membranes (AEMs) have shown promising characteristics to overcome some of the problems associated with CEMs; the advantages of AEMs being selective transport anionic charge carriers, lower crossover of cationic redox couples, and facile reaction kinetics in energy conversion processes. These unique properties of AEMs result mainly from the density and distribution of positively charged functional groups, along with a macromolecular polymer backbone. As a result, there has been an increasing demand for the development of AEMs with better selectivity, higher chemical stability and conductivity, and a lot of work has been carried out in this area. The aim of this review is to discuss developments in the synthesis and applications of AEMs in the field of electrochemical energy conversion and storage, on which many researchers have been working in recent years.
This review covers recent advancements and future perspectives of AEMs for energy conversion and storage systems such as fuel cells and redox flow batteries.
As the digitalization of the safety instrumentation and control (I&C) systems in the nuclear field causes very complex interactions between their components and difficulty in securing quantitative ...failure information of each component, there are considerable challenges in analyzing them via probabilistic safety assessment (PSA), the typical safety analysis framework of existing safety I&C systems. This study proposes a new approach to resolve these challenges. The suggested method develops a system model based on the systems-theoretic accident model and processes (STAMP) philosophy and assigns weights to specific components according to design information and operation strategies instead of quantitative failure information. Based on the assigned weights, the importance of each component is derived by calculating the effect of a single component failure on the overall I&C functions. The methodology is explained through simple examples and validated with an analysis of a real-world system. The proposed approach is expected to be useful in deriving insights from the design stages to the improvement stages for more diverse I&C systems by enabling quantitative importance analysis without failure information.
Genome editing is crucial for genetic engineering of organisms for improved traits, particularly in microalgae due to the urgent necessity for the next generation biofuel production. The most ...advanced CRISPR/Cas9 system is simple, efficient and accurate in some organisms; however, it has proven extremely difficult in microalgae including the model alga Chlamydomonas. We solved this problem by delivering Cas9 ribonucleoproteins (RNPs) comprising the Cas9 protein and sgRNAs to avoid cytotoxicity and off-targeting associated with vector-driven expression of Cas9. We obtained CRISPR/Cas9-induced mutations at three loci including MAA7, CpSRP43 and ChlM, and targeted mutagenic efficiency was improved up to 100 fold compared to the first report of transgenic Cas9-induced mutagenesis. Interestingly, we found that unrelated vectors used for the selection purpose were predominantly integrated at the Cas9 cut site, indicative of NHEJ-mediated knock-in events. As expected with Cas9 RNPs, no off-targeting was found in one of the mutagenic screens. In conclusion, we improved the knockout efficiency by using Cas9 RNPs, which opens great opportunities not only for biological research but also industrial applications in Chlamydomonas and other microalgae. Findings of the NHEJ-mediated knock-in events will allow applications of the CRISPR/Cas9 system in microalgae, including "safe harboring" techniques shown in other organisms.
Hybridizing two known antimicrobial peptides (AMPs) is a simple and effective strategy for designing antimicrobial agents with enhanced cell selectivity against bacterial cells. Here, we generated a ...hybrid peptide Lf-KR in which LfcinB6 and KR-12-a4 were linked with a Pro hinge to obtain a novel AMP with potent antimicrobial, anti-inflammatory, and anti-biofilm activities. Lf-KR exerted superior cell selectivity for bacterial cells over sheep red blood cells. Lf-KR showed broad-spectrum antimicrobial activities (MIC: 4-8 μM) against tested 12 bacterial strains and retained its antimicrobial activity in the presence of salts at physiological concentrations. Membrane depolarization and dye leakage assays showed that the enhanced antimicrobial activity of Lf-KR was due to increased permeabilization and depolarization of microbial membranes. Lf-KR significantly inhibited the expression and production of pro-inflammatory cytokines (nitric oxide and tumor necrosis factor-α) in LPS-stimulated mouse macrophage RAW264.7 cells. In addition, Lf-KR showed a powerful eradication effect on preformed multidrug-resistant Pseudomonas aeruginosa (MDRPA) biofilms. We confirmed using confocal laser scanning microscopy that a large portion of the preformed MDRPA biofilm structure was perturbed by the addition of Lf-KR. Collectively, our results suggest that Lf-KR can be an antimicrobial, anti-inflammatory, and anti-biofilm candidate as a pharmaceutical agent.
Objectives
Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) entry into the host cells depends on the expression of angiotensin‐converting enzyme 2 (ACE2) and transmembrane protease serine ...2 (TMPRSS2). We investigated the distribution of ACE2‐ and TMPRSS2‐expressing cells in various oral tissues to identify the underlying mechanism of oral manifestations in patients with coronavirus disease 2019.
Subjects
We analyzed the expression patterns of ACE2 and TMPRSS2 in the oral mucosa (tongue, palate, and buccal mucosa), trigeminal ganglion, vessels, and salivary glands of 9 Sprague‐Dawley rats using immunohistochemistry and immunofluorescence.
Results
ACE2 and TMPRSS2 were strongly expressed in the intermediate layer of the squamous epithelia of tongue papillae and buccal mucosa. ACE2‐ and TMPRSS2‐positive cells were observed in the taste buds of the tongue. Additionally, ACE2 and TMPRSS2 were co‐expressed in the ductal epithelium and acinar cells of salivary glands. Furthermore, both ACE2 and TMPRSS2 were stained in the neuronal cell body of trigeminal ganglia, but not in Schwann cells. Moreover, ACE2 and TMPRSS2 were expressed in capillaries, but not in venules/arterioles.
Conclusions
SARS‐CoV‐2 can spread the suprabasal area of squamous epithelia of the oral mucosa, invades taste bud, trigeminal nerve, parotid gland, and microvessel, resulting in oral manifestations.
We report high-performance flexible nanogenerators (NGs) based on a composite thin film, composed of hemispherically aggregated BaTiO3 nanoparticles (NPs) and poly(vinylidene ...fluoride-co-hexafluoropropene) P(VDF-HFP). The hemispherical BTO–P(VDF-HFP) clusters were realized by a solvent evaporation method, which greatly enhanced piezoelectric power generation. The flexible NGs exhibit high electrical output up to ∼75 V and ∼15 μA at the applied force normal to the surface, indicating the important role of hemispherical BTO clusters. Besides, the durability and reproducibility of the NGs were tested by cyclic measurement under bending stage, generating the output of ∼5 V and ∼750 nA. The approach we introduce here is simple, cost-effective, and well-suited for large-scale high-performance flexible NG fabrication.
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